The peanut monument in Ashburn, Georgia was officially recognized as a state symbol in 1998. The peanut is also the official state crop of Georgia.
The big peanut monument, or "The world's largest peanut" was erected in 1975 as a tribute to the peanut processing industry that caused Ashburn to become known as "The Peanut Capital of the World." Ashburn is also home to a peanut museum and the world's largest peanut-shelling plant (The Golden Peanut Company).
The peanut (Leguminosae) probably originated in Brazil or Peru. Peanuts are not really nuts - they are legumes (peas and beans are also legumes). Peanuts grow underground, unlike nuts (like walnuts, almonds, etc) that grow on trees.
Information sourced from StateSymbolsUSA.org