Truffle, e.g

• Grow naturally in southwestern Europe
• A common European plant having edible tubers with the flavor of roasted chestnuts
• Edible subterranean fungus of the genus Tuber
• Any of various highly prized edible subterranean fungi of the genus Tuber
• Pod of the peanut vine containing usually 2 nuts or seeds
• Plant with edible tuber

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Peanut \Pea"nut\, n. (Bot.) The fruit of a trailing leguminous plant ( Arachis hypog[ae]a ); also, the plant itself, which is widely cultivated for its fruit. Note: The fruit is a hard pod, usually containing two or three seeds, sometimes but one, which ...

Wiktionary Word definitions in Wiktionary
n. 1 Any of various roots, tubers, or pods that grow underground. 2 # A tuber belonging to the species (taxlink Bunium flexuosum species noshow=1), (taxlink Carum bulbocastanum species noshow=1), (taxlink Conopodium denudatum species noshow=1), or (taxlink ...

Wikipedia Word definitions in Wikipedia
Earthnut is a common name for several unrelated plants which produce a subterranean edible seed, fruit or root Earthnut may refer to: Truffle Peanut Roots and tubers: Lathyrus tuberosus Conopodium majus Bunium persicum