Phaeolus schweinitzii

Common Name: Dye Polypore
Description: Fruit body sometimes an irregular cushion, but usually subcircular, 10-30 cm across, with a short, thick stalk; deep sulphur yellow becoming rust- or dark brown, finally blackish when old; soft and spongy, upper surface concave, rough and hairy or woolly, concentrically grooved at first. Stem brown, very short, thick, merging into cap and with the tubes decurrent down it.
Habitat: parasitic on conifers, usually growing from the roots. Found over most of North America.
Edible: Not edible.

Source: Mushrooms of North America by Roger Phillips.