This was found by David Wong. Only a single one. There is no gills on the underside. Could this be Leratiomyces ceres ? Kindlt ID please, thank you.
Good ID direction to go in David: Leratiomyces used to be part of Stropharia, and it looks like you have a Stropharia there. When the mushroom grows more and the cap opens up, the fluffy white inner veil covering the gills will break open.