What this coin looks like (obverse, reverse, mint mark location, special features, etc.):
One major variety is the 1824/2 Overdate Error of the Coronet Head Large Cent (Penny). This variety features an 1824 date struck over an 1822 date which resulted in parts of the leading "2" still being visible under the "4" as depicted by the arrows in the example image of the coin above.
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD