What this coin looks like (obverse, reverse, mint mark location, special features, etc.):
There were to major varieties of the 1831 Capped Bust Quarter. One variety had small letters on the reverse (as depicted above) while the other had larger letters. The letters to look for are in the words "UNITED STATES OF AMERICA" and the denominational "25 C". The difference between the large letters vs small letters is depicted below in the example comparison image of the coins:
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD