Have you ever looked at the spare change in your pocket (even the lint) and considered it a nuisance? The next time you rummage through your spare pocket change for parking or coffee money, consider that there may be a gold or silver coin, or a florin or doubloon worth a small fortune. Coins released with mistakes and accidental engravings can become quite rare and valuable, and coin collector’s are always buying and selling coins at auctions or even via eBay for hefty profits. Here are five rare U.S. gov mint coins, bullion coins, silver dollars, and more to keep an eye out for:

1. The 2000 Sacagawea Cheerios Dollar

As the name indicates, this rare coin made its way accidently into 5,500 boxes of Cheerios cereal. The U.S. Mint meant to promote the new 2000 Lincoln Cent, dubbed “the Golden Dollar”, via 10 million or so boxes of America’s favorite cereal. However, several coins were accidentally struck from a different set of master dies than the regular Sacagawea Dollar, this one bearing enhanced eagle tail feathers on the reverse side of the coin. With only 70 total Sacagawea Cheerios Dollars in existence today, they are valued at up to $25,000 USD per coin, depending on the grade.

2. 1794 Flowing Hair Silver Dollar

With less than 1,800 of these particular Flowing Hair Silver Dollars produced, this coin sells for a whopping 10 million dollars USD today, making it a truly rare find. The front of this silver dollar features Lady Liberty with her flowing hair—while the back is marked by an American eagle. The Flowing Hair dollar was the very first dollar coin issued by the United States federal government. The coin was minted in 1794 and 1795, following a study by Alexander Hamilton and President George Washington who urged Congress to establish a national mint. This particular coin was based on the Spanish dollar, which was popular in trade throughout the Americas.

3. The 1787 Brasher Doubloon

Minted by New York City goldsmith, Ephrain Brasher, in the late 18th Century. The Brasher Doubloon is marked with a state seal and rising sun on the front side. The back of the coin depicts the American eagle and shield—the rarity is Brasher’s signature, signed EB on the eagle’s wing. This rare coin has fetched between $5 and $9.36 million at savvy collector’s auctions.

4. The 1343 Edward III Florin

Also known as the “Double Leopard”, the rare King Edward III florin is considered one of the world’s oldest and most expensive finds among collectors. Just one of three pure gold coins in existence, this florin depicts the Royal Cross inside a quatrefoil on the reveres—while the front shows King Edward III sitting his throne flanked by two leopards’ heads on either side. Today, two of 1343 Edward III Florin reside in the British Museum in London, worth an estimated $6.8 million USD.

5. The 2007 $1 Million Canadian Gold Maple Leaf

Considered a novelty coin, the $1 million Canadian Gold Maple Leaf coin weighs in at approximately 220 pounds of pure gold. Minted as a promotional showpiece for the Canadian Mint’s one-ounce Gold Maple Leaf coin, this coin currently holds the Guinness Book of World Record as the world’s largest gold coin (since 2007). At a massive 50 centimeters (or 20 inches) wide and over an inch in thickness, the front of the Gold Maple Leaf depicts Queen Elizabeth II, with a Canadian maple leaf on the reverse. The coin was most recently sold at auction for 3.27 million euros, or just over $4 million USD.