What this coin looks like (obverse, reverse, mint mark location, special features, etc.): One major variety is the 1810/09 Classic Head Large Cent (Penny) overdate error. This variety depicts an 1810 date struck over an 1809 date. This resulted in the last two digits "09" appearing under the "10". This can be clearly identified by noticing most of the underlying "0" showing up around the "1" and part of the underlying "9" showing up below the last "0". The differences between the normal date vs the 1810/09 overdate can be seen in the example comparison image above.
Coin value chart: Typical coin prices, values and worth in USD based on grade/condition