A peanut was a type of legume. Crushed peanuts were used to make peanut butter.
In 2380, the word "peanut" was chosen by an exocomp as part of its new, non-robotic name, "Peanut Hamper". (LD: "No Small Parts")
In 2381, the Medical Ethics hologram simulation included a Klingon who had sustained paralysis following a spine injury while picking up a peanut, and wished that the Hegh'bat be performed. (LD: "I, Excretus")