Before the annual ceremony in the Forest Haven, Elma is standing next to the Great Deku Tree. If the player has a Deluxe Picto Box then a figurine can be made before the Koroks leave. After the annual Korok Ceremony, Elma can be found on Needle Rock Isle, sowing trees and spreading the Great Deku Tree's forest.
Elma's name is similar to Elm, a type of tree. This is appropriate, given the tree-like nature of Koroks.