Roasted Tree Nut is a consumable Meal in Zelda: ToTK, it is listed as recipe #195. When consumed it restores hearts; the number of hearts restored increases when more materials are used.

Chickaloo Tree Nut in Zelda: Tears of the Kingdom is an item that can be consumed or used in cooking meals to boost health, stamina, or add temporary status effects.

Keep your eye out for apple trees. There are also fruits that have elemental properties and can be fused to items like arrows for elemental effects. Below is a listing of all fruit in-game.