How found: Defeat the boss of Woodfall Temple and step into the blue light. You'll appear in a room unconnected to the rest of the dungeon; hack through the vines to the north and speak with the Deku Princess. Capture her in a bottle, then return to the Deku Palace and release her in front of the Deku King. Once the scene there has concluded, leave the palace and hop across the lilipads to the west. Enter the shrine and talk to the butler, then race through the long maze and speak with the butler again at the end. He'll give you the Mask of Scents.

    How used: While Link is wearing the Mask of Scents, mushrooms will appear as moving purple blobs. Mushrooms tend to be found in damp areas, such as the swamp and caves. Swipe the moving blob with a bottle -- it helps to Z-Target them -- and you'll receive a Magic Mushroom. Take the Magic Mushroom to Kotake's potion shop to make a Green Potion.