That's an EXTREMELY broad question because cents have been struck for over 200 years at 3 mints, so there are thousands of different types available. To name just a few of the more famous rarities:
1793 chain-link reverse
1909-S Indian head
1856 flying eagle
1877 Indian head
1909-S VDB Lincoln
and these error coins
1922 "plain"
1943 copper
1944 steel
1955 double die
Check the prices at a site such as www.coinclub.com/prices/, for example.
1909 vbd s
1916 S
1922 plain
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A rare date for wheat pennies would be 1909 S VDB.
No, the 1951 Lincoln cent is not rare.
Not really.
They were minted at the Philidelphi(no mint-mark), Denver(D) mints. These pennies are not rare.
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1943 silver pennies
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.
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.
None of the British South African Pennies are particularly rare (those dated 1923 through 1928, and 1933 and 1942 without a star at the end, are the most dear - at about US$3 to US$4 in Fine condition - nothing else is worth more than US$1.00 in Fine condition). Among Republic of South Africa one cent coins (not, strictly speaking, "pennies"), the only one worth more than US$1-2 is the 1965 with the name of the country in Afrikaans ("Suid-Afrika"), which is worth about US$100.00 in Very Fine condition and US$300.00 in Uncirculated condition.
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.
You would need to get it appraised by a coin dealer. 1944 the US was making pennies out of steel.. and they are very rare.
NO, cleaning them will probably reduce their value