Collectible coins, particularly in the context of the United States, include a variety of types such as commemoratives, bullion, and error coins. The 1851 California Gold Rush era generated significant interest in patterns, die trials, or experimental coins that were crafted to test designs before final production. The "P" refers to the Philadelphia Mint, where many early U.S. coins, including pattern issues, were produced. A specific example is the 1851 California gold coinage, which represents a fascinating intersection of history, art, and numismatics, with patterns often being rare and highly sought after by collectors.

Item Denomination Series Year Mint
1851 P$50P Humbert Copper Pattern BN P$50P Patterns & Die Trials 1851 California