What this coin looks like (obverse, reverse, mint mark location, special features, etc.): The 1955 Doubled Die Obverse DDO Lincoln Cent (Penny) is the most famous double die penny and error of them all. The obverse of this coin depicts one of the most prominent displays of doubling which makes it extremely popular and valuable. The motto "IN GOD WE TRUST" and the word "LIBERTY" are very clearly doubled as is the 1955 date as depicted in the example image above. It is very hard to miss this error so it is easy to tell the difference between the real one and the 1955 "poor mans" doubled die which is no where near as noticeable.
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD