Just make sure they are edible common field mushrooms. Many species are indeed poisonous. If in doubt , do not eat. Autumn is the time that mushrooms fruit and produce spores so you really only notice them now even though they produce very long filiments underground, many metres long. Soil is a substrate in which hundreds if not thousands of species of plants, animals, insects, fungi, bacteria and virus make their home. You are really fighting against the tide if you only want to actually see of those species, eg fescue or ryegrass lawn. I say knock or mow them off over the next 8 weeks, job done till next year.