A good mushroom for dying.

Wikipedia says:
Phaeolus schweinitzii, commonly known as velvet-top fungus, dyer's polypore, or dyer's mazegill, is a fungal plant pathogen that causes butt rot on conifers such as Douglas-fir, spruce, fir, hemlock, pine, and larch. P. schweinitzii is a polypore, although unlike bracket fungi the fruiting body may appear terrestrial when growing from the roots or base of the host tree. The fruiting bodies, appearing in late summer or fall, commonly incorporate blades of grass, twigs, or fallen pine needles as they grow. As these fruiting bodies age, the pore surface turns from yellow to greenish yellow, the top becomes darker, and the flesh becomes harder and more wood-like.

P. schweinitzii is native to North America and Eurasia, and has been identified as an exotic species in New Zealand, Australia, and South Africa.

As its common name suggests, the dyer's polypore is an excellent natural source of green, yellow, gold, or brown dye, depending on the material dyed and the mordant used.

MushroomExpert.com says:
This mushroom is a classic "butt rot" fungus, attacking trees through their roots and producing decay in the root system and the heartwood of the lower portion of the tree (up to about 10 or 20 feet above ground). The result is a weakened, or even hollow, tree base--which makes the tree more susceptible to windthrow, especially if other agents (beetles, for example) have combined destructive forces with the fungus.