I bought a house. The backyard has not been maintained. It was thick with trees, limited sun, and moisture. Removing the old rotten trees and trying to get rid of moss growth. Opening it up to the sun. Not done with the trees yet, but starting to think about he lawn phase. The issue is that there are years of leaves built up, moss, a lot of tree stumps cut to the ground, and tree roots. I want to place a few inches of top soil and plant grass with straw over it. Is it ok to put the soil over the thick leaves, old moss, and stumps? If so, any recommendations for soil thickness in inches or type of grass? Live in Western PA. Rains a lot.