Druid Pouch

Increases the Intelligence of the Hero by 1 when carried.

This small container is made of leather with a top flap that clasps to the bag with a single tooth. When touched to the owner's belt or any other article of clothing, it fastens itself there until released with a command word, thereby making it impossible to steal through sleight of hand.

Source
Tyrande can find one in Daughters of the Moon, chapter 2 of the Warcraft III night elf campaign, Eternity's End.