Mushroom

In the Zelda series, Mushrooms have played several small roles, most of which have been associated with magic.

A Link to the Past and Link's Awakening
In A Link to the Past, there is a mushroom found in the Lost Woods. In Link's Awakening, there is a Sleepy Toadstool in the Mysterious Forest. In both games, giving the mushroom to a Witch results in Link receiving Magic Powder.

Oracle of Seasons
In Oracle of Seasons, a mushroom is part of a required trading quest to obtain the Noble Sword.

Ocarina of Time and ''Majora's Mask
In Ocarina of Time, a mushroom used as trade to present a man with Magic Powder. In Majora's Mask, a mushroom in nothing more than an item to be sold.