Collectible coins can be categorized into various types, including bullion coins, numismatic coins, and pattern coins. In the United States, the term "Two and a Half Dollars" typically refers to the quarter eagle gold coins, which were minted from 1796 to 1933, primarily featuring designs by notable engravers like Augustus Saint-Gaudens. Privately issued patterns are experimental coins struck by private mints or individuals that often serve as prototypes for proposed designs or denominations, typically lacking official authorization from the U.S. government. These patterns can be highly sought after by collectors due to their rarity, unique designs, and historical significance.

Item Denomination Series Year Mint
United States of America 1803 N/A Privately-issued "Patterns" $2.50 $2.50 (Two and a Half Dollars) Privately-issued "Patterns" 1803 N/A