I don not have a picture, but I found what I think is a fungus in my shed on a rotting piece of plywood floor. The fugus looks like an orangey brown wavey pile almost like an all purpose grease. I noticed when I blow on it, a puff of white dust/smoke comes from under it. When I poked it with a stick, it was brittle, but then smushy. It really freaks me out. I wish I had a digital camera. I may borrow one if no-one has ever heard of this. I found it once before and broke it up....a couple weeks later, it is back so I am sure that it is something that is growing. Any help would be appreciated.
Puffballs (Basidiomycota) come in my mind due to the dust/smoke feature you've described, but I can't be fully sure of that unless you may provide us a picture, which is something really useful for any specific identification. Just a small warning about puffballs : some species can be harmful if large quantities of spores are inhaled, but that's going likely to happen only intentionally, so it's nothing serious to worry about. Regards