I know this thread is old and you probably already have solution, but here it is anyways.

I would for sure try to get rid of them. The mushrooms aren't the problem but the mycelium from which the mushrooms come from is. The older,more colonized, and denser the mycelium gets it will grow all around the roots. When it surrounds the roots it will most likely lock out all nutes and maybe even water. This stuff is truely amazing and spreads incredibly fast. In Oregon one mycelium was responsible for killing an entire forest, although the mycelium was 2,200 years old and the size of 1,655 football fields. This is considered to be the largest organism in the world. I have no ideas on how to get rid of it though. Once mycelium is established well enough to fruit (produce mushrooms) it can survive extreme temperatures and drought. Maybe a fungicide?