Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
helvella (helvēla, Paul. ex Fest. p. 103 Müll.), ae, f. dim. [‡ helus, i. q. olus], a small potherb: fungos, helvellas, herbas omnes ita condiunt, ut nihil possit esse suavius, Cic. Fam. 7, 26, 2; cf.: helvela olera minuta, Paul. ex Fest. p. 103: helvola λαχανάρια, Gloss. Philox.