Avid collectors of American notes and coins will often pay eye-watering sums for desirable items in mint condition. From the pennies and dollar bills you may just find lurking in your wallet or purse to historically important rarities that can fetch millions, and in some cases break records while doing so, read on to discover the US cash worth considerably more than its face value.

A number of 2005 Kansas state quarter coins, minted in Philadelphia, were incorrectly imprinted with the motto "In God we Rust" as a build-up of grease in the die meant the 'T' of 'trust' didn't print. These so-called "error coins", which are in circulation right now, can be worth anything up to $100 apiece depending on their condition.

It's always a good idea to check the serial numbers on the bills in your wallet or purse: after all, fancy serial numbers can command surprisingly high prices. For example: so-called "repeater" and "super-repeater" notes, which feature serial numbers that replicate the same one, two or three digits, can sell for up to $160, and sometimes significantly more, on eBay and similar auction sites.

Keep your eyes peeled for misprints too. Printing errors can range from bills with incorrectly colored seals and orientations that are off to upside down or double-printed serial numbers. By way of example, this 2006 dollar bill features a double-printed serial number, and sold on eBay for just under $200. The weirder the misprint, the more valuable the note is likely to be.

There's a likelihood that this coin could show up in your change, so look out for it. All US coins should have a mint mark, be it P for the Philadelphia Mint, S for the San Francisco Mint, D for the Denver Mint, and W for the West Point Mint. However, a number, thought to be no more than 150,000, of 1982 Roosevelt dimes were released in 1982 without a mark. If you spot one that lacks a mint mark next to the year stamp, it could be worth up to $300.

While rarely used, the $2 bill remains in circulation, though relatively few are printed these day. While they aren't worth much more than their face value, the red seal $2 notes that were issued in 1928 could be worth something. These crisply immaculate bills can fetch decent prices at auction – a particularly fine example sold recently on eBay for just under $380.

Thousands of Wisconsin state extra leaf quarters were issued in error by the Denver Mint in 2004. There are two varieties of the quarter available to find, which is incorrect due to the presence of an extra cornstalk leaf in its design. Variety one is the low leaf version, which depicts an arched leaf jutting out sideways on the reverse of the coin, while variety two is the high leaf version, which shows an additional leaf poking out of the cheese wheel that touches the corn husk leaf. These coins can be worth up to $400 each – if you find one in your change, make sure you hang onto it!

An estimated 20,000 examples of the 1972 doubled die pennies slipped through the net, many of which are still in circulation. One of the most common minting errors, doubled die coins are created when the die imprints a misaligned image on the coin, giving the lettering and numbers a blurred finish. The fuzzy effect is pretty pronounced on these Abe Lincoln cents, and they're worth up to $500 each.

Another type of fancy serial number bill is the so-called "star note", which features an asterisk at the end of the serial number. These are printed to replace faulty notes and, since no two serial numbers can be the same, an asterisk is swapped in at the end of the serial number in place of a letter. Most aren't worth a lot more than their face value, but the most valuable can fetch up to $500, so it's worth keeping your eyes peeled.

In 1999, the Philadelphia Mint issued around 400 Lincoln Memorial pennies with a space between the letters "A" and "M" in the word "America" on the coin's reverse side.  This subtle spacing error is the giveaway clue that you could have something of value on your hands. Other coins issued have virtually no space between the letters, which look like they're touching. The so-called "Wide AM" coins are now worth around $500 apiece. 

Up to 24,000 doubled die pennies were released into circulation by the Philadelphia Mint in 1955. Many of these ended up being spent on packs of cigarettes in New England vending machines: the price per pack was 23 cents, but the machines could only take quarters so the pennies were added to the packs to even up the price. These circulated coins, which feature the telltale blurred lettering and numbers on the reverse, can be worth up to $2,000 each.

Notes with serial numbers made up of identical digits are rare, with only one in 11 million bills printed boasting this type of detail. As a result, they're worth big bucks. Considered lucky by some, this dollar bill, which has a serial number entirely comprised of sevens, sold recently on eBay for $600. Even more impressively, a 2006 $100 bill with a ones-only serial number was available recently on the CoolSerialNumbers site for $4,500.

Notes that have serial numbers with digits that ascend or descend are also pretty prized. Called "ladder bills", the most sought-after examples are bills that feature the so-called "perfect" ladder serial numbers: 12345678 and 87654321. Unsurprisingly, these notes are exceedingly scarce and represent only one-in-96-million bills printed, meaning they can sell for big bucks.

Five Sacagawea commemorative dollars have been found with transitional errors, according to Mint Error News. These mistakes occur when a coin is struck with a different metal composition from what has previously been used, before being fed into a coin press for the current year. These mega-rare coins can be worth up to $15,000 and, who knows, there might even be more of them out there...

Check your bills for low serial numbers, as these could make you some serious money. According to the experts, a redesigned $100 bill with the serial number 00000001 could fetch anywhere between $10,000 and $15,000. Other typically low serial number bills (00000100 or lower) can be worth a little less, realizing up to $1,000.

Dubbed “The King of Silvers” by collectors in the know, the 1933 $10 silver certificate had a print run of 216,000, but only 156,000 were ever released. Very few survive to this day and due to its "one-year type" status, these remarkable notes are tremendously valuable. While used examples in good condition can fetch up to $5,200, the finest grades can sell for as much as $70,500.

You'll have hit the jackpot if you discover one of these babies in your change. Astonishingly, only 50 of the 1969-S doubled die Lincoln pennies escaped the mint and made it into circulation – and it's safe to say that their value far exceeds one cent.

Michigan-based collector Michael Tremonti found one in 2007 while searching through a 50-coin roll and it was later valued at a sensational $126,500. Another sample of the coin sold in auction for $85,100 in 2007. It pays to check your change, people...

If you've got some very old bills stashed away at home, you might want to check for state-issued notes. After all, many of these are worth significantly more than their face value.

This Alaskan banknote, for instance, was printed during the state's famous Klondike Gold Rush and was among the first $5 bills issued by the First National Bank of Fairbanks. It was sold in 2012 by Heritage Auctions for an incredible $246,750.

During World War II, pennies were struck in zinc-coated steel, with copper reserved for the war effort. That said, a tiny batch was accidentally minted in copper, and it's believed that around 20 of the erroneous Philadelphia and San Francisco-minted coins are estimated to be floating around today.

In 1947, 16-year-old Don Lutes Jr. discovered one of the coins in his lunch money change. Lutes kept it until 2019, when he sold it at auction for a whopping $204,000, with Heritage Auctions describing the coin as "the Holy Grail of mint errors".

So how can you tell if you've got one of the incredibly rare 1943 copper pennies? Use a magnet. Steel pennies will stick, while the valuable copper rarities will not.

First minted in around 1652, this silver shilling is one of the earliest coins from Colonial New England. There are just a few-dozen known to exist, and while a shilling in 1650 is the equivalent of about $7 today, this example (pictured) sold for a whopping $351,912 at auction in November 2021, smashing past its original $300,000 estimate. The coin was originally minted in Boston but discovered a long way from home in a candy tin in Northumberland, England. 

Say hello to a truly unique 2004 $20 bill, which had a Del Monte banana sticker attached to it before being printed with its security numbering. Prior to being sold at auction, the one-of-a-kind note was valued at $57,500, which is nearly 3,000 times its face value. However, it defied all expectations in January 2021, when it sold in auction for a whopping $396,000 – a record price for a banknote with an error.

Unlike many other low serial number bills, you won't see this beauty in circulation – if only! This 1931 $10 silver certificate, boasting the serial number A00000001A, has been valued by numismatic experts at a cool $500,000. 

A prototype version of the US Mint's first dollar coin sold at Heritage Auctions in April 2021 for $840,000, way above its $350,000-$500,000 estimate.

The copper coin, known as a pattern, was reputedly discovered at the site of the first Philadelphia Mint back in the late 19th century. It's similar to the silver dollar coins that later went into circulation, bar the fact that it's missing the stars that appeared around the "flowing hair" portrait of Liberty. The coin was from the collection of Bob Simpson, the businessman and Texas Rangers co-chairman, who purchased it in 2008.

At the same Heritage Auction sale as the previous entry, this 1792 pattern sold for a staggering £1.26 million. Experts believe the coin was made as a potential prototype for the quarter dollar coin. It's one of two examples owned by the New-York Historical Society, and one of just four known to be in existence. The Society found its pair of coins back in 2003, while taking an inventory of its coin and medal catalog.

While around two-dozen specimens of the Philadelphia-minted 1943 copper penny are known to exist, just one example struck at the Denver Mint has been discovered. As a result, the truly unique coin is worth an absolute fortune.

In fact, the penny, which was discovered for the very first time in 1979, was sold for a jaw-dropping $1.7 million by New Jersey's Legend Numismatics back in September 2010.

Very few 1907 Rolled Gold Edge Eagle $10 coins are known to have survived to the present, and collectors have entered into fierce bidding wars to get their hands on these elusive coins.

One of the coins, referred to as the "finest example...known today", sold for $2.2 million at auction in January 2011. Over 6,700 people took part in the bidding war, which was hosted by Heritage Auctions in Tampa, Florida. 

According to Heritage Auctions, just 268 examples of the 1854-S Liberty Half Eagle were minted, of which only four are known about today. When the coin was discovered by an anonymous New England collector in 2018, experts thought it might be the same one that was notoriously stolen from the collection of Willis duPont in 1967.

Tests later confirmed it was a different coin, however, meaning it could be sold at auction. It fetched $2.16 million in 2018 and was sold again just three years later, netting a cool $2.4 million in its second-ever public offering in August 2021. 

Setting what was then a world record for a rare banknote sale, this 1891 red seal $1,000 treasury note sold for an astonishing $2.5 million at auction in 2013, far exceeding its estimate value of $2 million.

One of two surviving specimens, the high denomination note is every collector's dream acquisition. It features a portrait of George Meade, the US military man who played a crucial role in the American Civil War.

Worth millions more than its face value, the very first penny struck by the United States Mint is the Holy Grail cent coin for collectors.

Nicknamed after its engraver, Robert Birch, the "Birch Cent" is likely to have been handled by both George Washington and Thomas Jefferson, further adding to its prestige. With just 10 in existence, this particular coin was snapped up in 2015 for $2.6 million by delighted collector Kevin Lipton.

The world-famous 1890 Grand Watermelon $1,000 treasury note exceeded all expectations when it fetched a staggering $3.3 million at auction in 2014, making it the world's most valuable banknote.

The bill is so-named on account of the green zeros on the note's reverse, which have been likened to watermelons. Prior to this, the note was last sold at auction in 1970, when it went under the hammer for $11,000 ($79k in today's money).

Just five 1913 nickels bearing the Liberty Head design are still in existence – and they're highly valuable. Heritage Auctions sold one for $3.7 million in 2010 and another for $3.2 million in 2013. The most valuable example, the so-called Eliasberg Specimen, was purchased by a private collector from California for $5 million in 2007.

The highly covetable Flowing Hair dollar was the first dollar coin issued by the US federal government and is now the most coveted by collectors. This perfectly-preserved specimen from the Lord St Oswald-Norweb Collection went for just under $5 million at auction in 2017. Prior to that, the ultra-rare coin sold in auction for $242,000 in 1988, or $570k in today's money.

This exquisite $10 gold coin dated is 1804 but was actually minted in 1834 for President Andrew Jackson to offer as a diplomatic gift to officials in Asia. Today, only four examples of the coin are known to exist, with one selling via Heritage Auctions for $5.28 million in January 2021. 

Another multimillion-dollar coin that sold in 2021 is this 1861 Paquet Double Eagle coin, which was originally worth $20. It's been described as "by far the rarest regular issue Double Eagle", although with only two known to exist this isn't a surprise. One of the coins sold for a whopping $7.2 million at Heritage Auctions last August. The gleaming coin is named after Anthony Paquet (1814-1882), who was an assistant engraver at the United States Mint. 

Described as 'the King of American coins', only 15 examples of the 1804 Bust dollar – AKA the Bowed Liberty dollar coin – are known to exist and the finest Class I pieces command sky-high prices.

While they are dated 1804, the coins were actually struck during or after the 1830s. One specimen sold for $4.1 million in 1999, while another fetched $3.9 million at auction in 2013. Most recently, an example from the 1835 collection of the Sultan of Muscat sold for $7.68 million in August 2021. 

This 1822 Capped Bust Half Eagle briefly became the world's most valuable gold US coin when it sold for $8.4 million on 25 March 2021. According to the Professional Coin Grading Service (PCGS), the coin has only been sold a few times in the last century, with just three known examples in existence.

Unlike other entries on our list, however, this coin hasn't always been rare. Almost 18,000 copies of the coin were originally minted – so there are potentially more out there still waiting to be found. 

The finest example of just seven known 1787 New York-Style Brasher Doubloons, this gold coin hit the headlines in January 2021 when it sold for a huge $9.36 million via Heritage Auctions. Discovered in 1848, this particular coin caused a storm as it has only been publicly sold twice since its first discovery, reaching record prices both times. Prior to the 2021 sale, it went for $725,000 in 1979, holding the record of the world's most valuable coin for a decade. While it might no longer be the world's most valuable coin, it certainly comes very close to the top spot.

Currently the world's second most valuable coin, this 1794 Flowing Hair Dollar is the finest known example. Described as a "national treasure" by numismatic expert Steven Contursi, the historically important coin sold for an almost unbelievable $10 million at auction in 2013. That's twice the amount paid for the previous Flowing Hair Dollar mentioned in our round-up. 

An extremely rare Double Eagle coin sold for a record price of $18.9 million at a Sotheby's auction on 8 June 2021. The coin now holds the record for the most expensive ever sold, more than doubling the previous record. Remarkably, the coin's face value is just $20. It's value is due to the fact that the 1933 edition never actually entered circulation, with most returned to and melted down by the US government. However, it's believed that 13 coins did make it into circulation, and in 1944 the Secret Service declared that if any collectors possessed any of the coins, they would be considered stolen.

This coin was only able to be sold by a private collector after a legal battle between the United States Treasury and a former owner of the coin granted possession. The coin was then sold to the shoe designer Stuart Weitzman in 2002 for $7.6 million, which set a record at the time), before Weitzman put it up for sale again in 2021.

Now read about how the US dollar has changed over time