Collectible coins are items of numismatic interest often sought after by collectors and investors. One significant category includes trial coins or patterns, which are experimental pieces struck to test designs, compositions, or minting processes. An example is the 1874 ten-dollar pattern coins from the Philadelphia Mint, which were created as potential designs for the Gold Eagle but were never adopted for circulation. These coins are valued for their historical significance and rarity in the United States numismatic market.