A pea was a type of Earth vegetable.
Beverly Crusher's grandmother used to add peas to her vegetable soup. (TNG: "Attached")
In 3190, Ruon Tarka replicated a dish of cold mashed potatoes and a single pea (representing the control device) to model the Dark Matter Anomaly for Saru and Paul Stamets, and display the importance of "getting our hands dirty." (DIS: "The Examples")