Hilum: The scar on a seed that marks the point at which it was attached to the plant.*
Bean seeds have very obvious hilums.
From left to right in the picture: Mexican Red bean, Mung bean, Cranberry Red bean, Amish Nuttle bean, Rattlesnake bean, Hutterite Soup bean, and Black Valentine bean.
*Allaby, M. (2006). A dictionary of plant sciences (Revised ed.). Oxford: Oxford University Press.