Mushrooms are a fungus....when you pull them out see if straight vinegar from the bottle will kill it.......put a stick there to see if they come back in that spot....do several spots close.....bag & trash them don't mulch..........if that does not work.....lawn & garden store has funguscide spray mix or liquid...........keep children & pets away from that area until it is dry............wear appropiate gear.....stay away from tree roots.