Fruits can be found on some trees with orange trunks and olive-green leaves. They can be knocked off the trees by hitting the tree with a weapon/tool. The fruit will fall and then you can collect it. Fruit that has been knocked to the ground has small, white particles coming off of it in order to see easier. You can also shoot the fruit with a bow to make it fall down. There is usually only one fruit on a tree, but there can be two (this is very rare).