What this coin looks like (obverse, reverse, mint mark location, special features, etc.): One major variety of the 1946 Walking Liberty Half Dollar features a Doubled Die Reverse (DDR) error. Much of the entire reverse of the coin is doubled slightly. The doubling is most noticeable at the top of the words "E PLURIBUS UNUM". There is extreme doubling of the eagle's feathers as well and is very noticeable. These features are depicted by the arrows in the example image above.
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD