1. 1804 Silver Dollar: Commonly known as the "King of American Coins," only a handful of these coins exist today, and they are considered to be among the rarest coins in the world. The rarity of the 1804 Silver Dollar is attributed to a number of factors, including production delays and the melting down of some coins to create other denominations.
2. 1913 Liberty Head Nickel: The 1913 Liberty Head Nickel is famous for its unique history and low mintage. It was minted due to a misunderstanding between the Mint and the Treasury, and only a few dozen were produced before the design was changed. Today, these coins are highly sought after by collectors.
3. 1943 Copper Cent: In 1943, the United States Mint experimented with producing pennies from copper-plated steel due to the shortage of copper during World War II. However, only a small number of these copper cents were produced, making them extremely rare. Most copper cents from 1943 have a steel composition.
4. 1955 Double Die Obverse Penny: This coin is unique because of a doubling effect on the obverse (front) of the coin, which occurred due to a misalignment of the dies during the minting process. The 1955 Double Die Obverse Penny is one of the most famous error coins in US numismatics.
5. 1794 Silver Dollar: The 1794 Silver Dollar is significant because it was the first silver dollar coin produced by the United States Mint. It is highly valued by collectors and numismatists due to its historical importance.
6. 1894-S Barber Half Dollar: The 1894-S Barber Half Dollar is a rare mint error coin. The "S" mint mark on this coin indicates that it was minted in San Francisco, but an error occurred during production, resulting in a doubled die effect on the reverse of the coin.
These are just a few examples of rare US coins that are prized by collectors. Many other scarce and valuable coins exist, each with its own unique story and historical significance.