Well, let it be said that Alex and Ed gave you the toxic or, Monsanto approach to poisoning your environment. Pat gave the best advice on the problem you requested to solve. The rest of us gave you shit because of an apparent lack of interest in the subject you were trying to correct. Hopefully if your car's motor was making an odd clicking sound and you asked strangers hoe to fix it, you wouldn't accept the suggestion of pouring sawdust into the crankcase without checking the reasonableness of the assertion.
Not all ecological damage is done out of malice. Most of it is done by thoughtlessness. Hopefully, the next yard project you have, you will know that your actions have consequences. Working with nature, you won't have those cans of poison lying around the house for your toddlers to get into. Get the mushrooms identified. They are probably harmless.
Sorry for the rough treatment, but sometimes you have to hit a jack-ass between the eyes with a 2 x 4 to get its' attention ;o)