WordNet sense 1 (any of various highly prized edible subterranean fungi of the genus Tuber; grow naturally in southwestern Europe):

truffle, earth-ball

WordNet sense 2 (a common European plant having edible tubers with the flavor of roasted chestnuts):

Conopodium denudatum

WordNet sense 3 (pod of the peanut vine containing usually 2 nuts or seeds; `groundnut' and `monkey nut' are British terms):

goober, groundnut, peanut, goober pea, monkey nut