What did shakespeare mean by the word pignut?

In Shakespearean plays, the word 'pignut' is used to refer to a wild-growing groundnut, often associated with being small, round, and hard. It was widely consumed by the common folk in Shakespeare's time and was often used as sustenance by those in poverty or lower socioeconomic status. In some cases, it could also refer to a type of nut produced by the earthnut plant (Apios americana), which was historically abundant in North America.