Entoloma abortivum

The whitish gilled mushrooms are Entoloma abortivum. The misshapen masses are a species of Armillaria mushroom that have been parasitized by the Entoloma abortivum.

For years, field guides indicated that the aborted forms of Entoloma developed in response to being parasitized by Armillaria spp. such as Armillaria mellea. Recent work indicates that the relationship is the other way around, that is, Entoloma is the parasite and the aborted structures are Armillaria spp.