Whether you’re just starting out or have been collecting rare coins for years, you know just how much value some coins can have. You can buy and sell valuable coins at auctions or even online on websites like Ebay. Whether they’re gold, silver, bullion, made by the U.S. Mint or another mint, most rare coins have very subtle features that make them valuable, so make sure you don’t give away your coins before taking a look—you never know if you’ve come across a rare one. Here’s the 5 most valuable coins by the U.S. Mint you should be on the lookout for:

1. Saint-Gaudens Double Eagle
This gold coin is precious to those who collect it as a result of its rarity and the history that comes with it. Designed by Augustus Saint-Gaudens, the coin was minted between 1907 and 1933 with a mintage of 445,500; however, there are only 12 known to exist today. This coin features Lady Liberty standing in front of sun rays on the obverse and an eagle in flight on the reverse.

2. Flowing Hair Silver Dollar
This coin was the first silver dollar by the U.S. Mint, making it a very valuable coin for collectors. Minted in 1794 with only 1,758 coins produced, there are now only 120-130 known surviving coins. If you happen to come across a coin featuring Lady Liberty with her hair flowing back and the flip side with an American eagle, you’ve got yourself a rare Flowing Hair Silver dollar—just make sure it’s authentic before spending a lot of money.

3. Lincoln Head Copper Penny
This copper penny was created during World War II and displays a side profile of Abraham Lincoln as well as a description of ‘ONE CENT’ on the other side. Pennies, typically made with steel, had a batch of these mistakenly made with copper, which is why the coin is rare and valuable today. About 20-40 of these coins are still around, but be cautious when shopping for one as this particular coin is often counterfeited—if it sticks to a magnet, it’s made of steel and inauthentic.

4. Edward III Florian
This coin, sometimes referred to as the Double Leopard, features King Edward III sitting on his throne with two leopard heads at his sides, and the reverse side displays the Royal Cross in quatrefoil. The Edward III Flroian has been around for almost 6 centuries and is estimated, and if you manage to get one, you will have 1 of just 3 of these coins still in existence.

5. Umayyad Gold Dinar
This gold coin features intricate, eye-catching designs and is rare because it was minted for a brief period of time during the Umayyad dynasty. This coin is desirable due to its unique appearance with 3 lines of inscription in addition to its rich history.