The cornucopia, often called the "horn of plenty," is one of the most iconic symbols of Thanksgiving in the United States. Pictured overflowing with fruits, vegetables, grains, and nuts, it evokes images of harvest bounty and gratitude. But this emblem has roots far deeper than the American holiday, stretching back to ancient mythology and evolving through centuries of cultural exchange. Understanding the cornucopia's origins and its integration into Thanksgiving traditions reveals how a classical motif became a cornerstone of a uniquely American celebration of plenty, community, and thankfulness.