You have mold in your home. Wait- before you run out of the house screaming, please remember that mold is ubiquitous. The nice smell of fall leaves is actually the smell of decay and … mold. The real question with your home is this: do I have harmful mold spores in sufficient quantity to be a health hazard to me and my family?
A basic mold air test can answer that question by comparing the mold count inside the home to that outside the home (taken as a control sample).