Mask of Scents

The Mask of Scents is the prize you get by beating the Deku Butler's challenge after finishing the Woodfall Temple. It allows you to sense the smell of the mushrooms in the Mysterious Forest on Majora's Maks.

You can also get a mushroom scent in the Clock Tower. On any day, go to the Stock Pot Inn and enter the third room on the 2nd floor, there you will find some shorts, put on the Mask of Scents to get the aroma in an empty bottle. Remember you can trade the mushroom at Witch's Hut to get a Blue Potion.