I've never seen mushrooms like this. We now have at least 6 of these large white round mushrooms almost the size of a basketball. They seem to be in the area near the bushes which are landscaped with mulch. Are these things poisonous? Are they valuable? Do people eat them? I have no idea. Should I just cut them out and throw them away? Help, please. Not that it matters, but we live in the North East (Baltimore). Thank you.