According to Stamets in Growing Gourmet and Medicinal Mushrooms, V. volvacea mycelium dies when temperatures drop below 45 degrees F. Means this would have to have been inoculated within the last 5-6 months? Is that possible? But Stamets also says it is also found "in eastern North America in hot houses, composts, or soils, especially in the southeastern states. Discarded experiments from the University of British Columbia in Vancouver, Canada are suspected in creating a recurring patch of the Paddy Straw mushroom which persisted for neraly a decade. (Kroeger 1993). Stamets also says it growing naturally on rice straw, sugar cane residue, leaf piles, compost heps during period of warm weather. First time I’ve heard it growing from a stump, so it could be a new species.
