Collectible coins encompass various types, including commemorative coins, bullion coins, and error coins, which hold value for collectors and investors. In the United States, the twenty-cent piece, issued primarily in the mid-19th century, is a notable example of a challenging collectible due to its limited mintage. Patterns and trial coins are specialized types that serve as test strikes or prototypes for potential new coins, often made in small quantities, making them highly sought after in numismatic circles.

Item Denomination Series Year Mint
United States of America 1874 Philadelphia Patterns & Trial Coins 20¢ 20¢ (Twenty Cents) Patterns & Trial Coins 1874 Philadelphia
United States of America 1875 N/A Patterns & Trial Coins 20¢ 20¢ (Twenty Cents) Patterns & Trial Coins 1875 N/A
United States of America 1875 Philadelphia Patterns & Trial Coins 20¢ 20¢ (Twenty Cents) Patterns & Trial Coins 1875 Philadelphia