Collectible coins, such as the 25-cent Washington Quarters, are often sought after by numismatists for their historical significance and rarity. The 1991 Washington Quarter, minted in San Francisco, features the unique "S" mintmark, indicating it was produced at the San Francisco Mint. These coins can vary in value based on their condition, rarity, and demand among collectors, particularly if they are part of a limited production or special release series.

Item Denomination Series Year Mint
1991-S (San Francisco) Washington Quarters 25¢ (Twenty Five Cents, Quarter) Washington Quarters 1991 San Francisco