What this coin looks like (obverse, reverse, mint mark location, special features, etc.):
One major variety is the 1820 Large Date Coronet Head Large Cent (Penny). This coin features a date with larger numbers. The most notable feature is that the "2" will have a flat tip which makes it easily distinguishable from the small date variety which has a curled tip on the "2". The difference between the 1820 Small Date vs Large Date penny can be seen in the example comparison image of the coins below:
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD