This may be the Dark-stalked Bolete (Leccinum atrostipitatum). You can tell this is a Bolete mushroom because it has tubes not gills underneath. Most mushrooms have gills, but boletes resemble many of the polypores with their tubes. They are sometimes called sponge mushrooms, an appropriate name, according to George Barron in his fine field guide "Mushrooms of Ontario and Eastern Canada".