The Lincoln cent is a one-cent coin that has been produced by the United States Mint since 1909. There have been several key dates for Lincoln cents, which are considered to be particularly rare and valuable. These key dates include:
1909-S VDB - This coin is rare because it was the first year of production for the Lincoln cent and because it was produced at the San Francisco Mint. It is considered to be one of the most valuable Lincoln cents.
1914-D - This coin is rare because it was produced at the Denver Mint and only a small number were made.
1922-D No D - This coin is rare because the Mint accidentally left off the "D" mint mark, which indicates that it was produced at the Denver Mint.
1931-S - This coin is rare because it was produced at the San Francisco Mint and only a small number were made.
1955 Double Die Obverse - This coin is rare because it was struck with two different dies, which resulted in a doubling of the design on the obverse (front) of the coin.