What this coin looks like (obverse, reverse, mint mark location, special features, etc.): One major Coronet Head Large Cent (Penny) variety is the 1820/19 overdate error. This coin features an 1820 date struck on top of an 1819 date. This resulted in a very prominent portion of the underlying "1" from "19" being seen under the "2" in "20". In some cases the "1" and "8" are slightly doubled as well. These features can be seen in the example image of the coin above.
Coin value chart: Typical coin prices, values and worth in USD based on grade/condition