Carpet has mushrooms growing along wall

As a followup: husband came home. Removed drivers side console, located 2 slightly rusty screws and a very tiny line/streak of water. He decided it was coming from outside drivers top of the window. He pulled up a very small area of wet carpet about 1 inch by 4 inches. We got rid of the pad underneath and dried the wood. It wasn't very soft and the area was very small. We had a local guy come and he says it is not black mold but a carpet bacillus/fungus and he doused it with something. Now we have a fan drying that area. We will keep the area as it is and keep an eye on it and if it stays dry we will cover it later. He resealed and recaulked that window once again. He just did that in May. It couldn't have been more then a hairline crack. We store it in our driveway and a wild turkey has been on the roof more then once. We despise rubber roofs and carpet and here we are with both. We are upgrading and going fulltime in a few years and be assured there will be no carpet and no rubber roof. Unfortunately we do not have a pole barn to store it.