Collectible coins are a category of numismatic items valued for their rarity, historical significance, and demand among collectors. The Liberty Head Double Eagles are a specific series of gold coins issued by the United States from 1849 to 1908, featuring the iconic Liberty design. The 20-dollar denomination is prominent within this series, and the 1878 coin is particularly sought after due to its limited mintage and unique characteristics. These coins, made of 90% gold and 10% copper, are emblematic of American currency history and often attract collectors and investors alike.