Gent regularly tucking into prizewinning mushroom

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Champignon \Cham*pi"gnon\, n. [F., a mushroom, ultimately fr. L. campus field. See Camp .] (Bot.) An edible species of mushroom ( Agaricus campestris ). Fairy ring champignon , the Marasmius oreades , which has a strong flavor but is edible.

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"mushroom," 1570s, from Middle French champignon (14c.), with change of suffix, from Old French champegnuel , from Vulgar Latin *campaniolus "that which grows in the field," from Late Latin campaneus "pertaining to the fields," from campania "level country" ...

Wiktionary Word definitions in Wiktionary
n. ''Agaricus bisporus'', the mushroom species most commonly used in cooking