In Mushrooms Demystified, Volvariella bombycina keys out easily: The Volvariella genus is marked by mushrooms with close, pinkish gills; a well-developed sac-like volva (but without an annulus or partial veil); and a central stalk. Once you're there, it's smooth sailing: This mushroom is not growing on other mushrooms and the cap is wider than 5 cm at maturity.
Volvariella bombycina grows on wood and the cap has long white hairs. The cap of this specimen measures 8.5 cm across. The stem: over 10 cm long; 7 mm wide at apex, enlarging to 13 mm at base.
Arora says it's edible "and according to reports, choice."
It's a stately mushroom, and it's time for me to invest in a good camera to rightly report wonders like these.