Deku Nut Upgrade 1
At the start of Ocarina of time you are able to carry up to 20 Deku Nuts. They are useful for stuning enemies so that you can attack. In order to get the first Deku Nut upgrade, you must go to the Forest Stage, located in the Lost Woods, and show the Deku Scrubs the Mask of Truth. Then go and speak to the Forest Stage Leader, who will tell you that all of the Deku Scrubs agree that you have a horrible face, but they will reward you with the a Deku Nut upgrade.