Collectible coins, particularly in the United States, encompass a wide range of types, including patterns, which are trial pieces created to test designs and compositions before mass production. The P 5, also known as the 1866 Pattern Five-Cent Piece, is a notable example that features a distinctive design not released for circulation, making it highly sought after by collectors. Patterns like the 1866 P 5 are often valued for their rarity and significance in numismatic history. These coins typically showcase variations from standard issues, offering insights into the evolution of American coinage during that era.