What this coin looks like (obverse, reverse, mint mark location, special features, etc.):
The 1981 Type 1 Filled S Washington Quarter has a smaller S mint mark which is partially filled in and not as clear and is only found as a proof coin. Depicted below is an example comparison image between the type 1 filled "S" vs type 2 clear "S":
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD