Carrot

Carrot is an item that appears in Super Mario Land 2: 6 Golden Coins. It transforms Mario into Rabbit Mario, but Wario also uses it to transform into Rabbit Wario.

Carrots also appear in Super Mario Advance (and strangely not in the original Super Mario Bros. 2 and other remakes of said game) as platforms that would bounce up out of hills and help Mario and company reach higher lands. They only appeared in two levels, though.

Carrots later appear in Mario Kart Arcade GP 2 as items. However, these carrots have bunny ears atop them.