A rare date for wheat pennies would be 1909 S VDB.
No, the 1951 Lincoln cent is not rare.
Not really.
2011 Lincoln cents are not rare. It just takes some time for "current year issue" coins to make their way into circulation.
They were minted at the Philidelphi(no mint-mark), Denver(D) mints. These pennies are not rare.
A rare date would be 1909-S VDB.
Uh, the word "everyday" means "ordinary or commonplace" so something that's commonplace can't be rare. If you're asking what are rare dates for Lincoln pennies please see the Related Question for more details.
Indian head pennies were no longer minted after 1909, so a 1922 Indian head penny would be quite rare.
NO, cleaning them will probably reduce their value
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Some rare U.S. pennies are: 1943 copper cents, 1922 no mintmark cents and the 1955 doubled die cents.
No. 2.4 BILLION were minted, and there are no known major varieties.