Collectible coins are valuable pieces of numismatic history, often sought after by collectors and investors. Notable examples include Morgan Dollars, which were minted from 1878 to 1904 and again in 1921, featuring the iconic design by George T. Morgan. The twenty-dollar gold piece, often referred to as the Double Eagle, is another significant collectible, with various designs and notable issues produced in the United States, including the St. Gaudens and Liberty Head series. Collectors often focus on factors such as mint mark, rarity, condition, and historical significance when evaluating these coins.