Some mushrooms may grow on trees, decomposing leaves, dung, mulch, soil or compost, feeding off the dead or decaying matter in those substances. Commercially grown mushrooms are often grown in a combination of manure and straw. The growing medium for wild mushrooms may not be easily visible, such as a dead vegetation under the ground. Many wild mushrooms, like morels (Morchella) are found at the base of trees and among dead leaves on the forest floor.