What this coin looks like (obverse, reverse, mint mark location, special features, etc.): The US Mint produced a 1936 Doubled Die Obverse (DDO) Lincoln Wheat Cent (Penny) error. This can best be identified by noticing the doubling of the words in the motto "IN GOD WE TRUST" and the word "LIBERTY". The most prominent doubling is of the date 1936 as depicted in the example image of the coin above. Source image for example above is courtesy of Heritage Auctions.
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD