Why do I have mushrooms popping up in my yard? I had my lawn professionally aerated and overseeded in early spring and now I am seeing mushrooms throughout the lawn.
Personally I wouldn't worry about the mushrooms. Their appearance likely doesn't have anything to do with the lawn treatments you did, fungal spores are just in the environment & will grow where they find suitable habitat.
If they bother you, you could pick them as they appear & toss them in the compost. Alternately, you could apply fungicide to the lawn, but I personally would not, as fungus (especially their underground network of mycellium) are actually part of a healthy environment.