Mosses are shade-loving and prefer moist conditions. You need to look for shady and moist areas. You can find them on the ground, on the rock, on living trees and fallen logs.
You may even find it in your backyard where moisture and shade are there.
Moss can be found in the forest too. While collecting the moss from wood, collect along with a layer of wood, because is used to it. You can even collect the dried moss.