I don't see the 'sock' at the base of the stipe. It's a white hyphal cushion from which the mushroom develops in M. candidus. This looks more like Campanella. They are closely related. C. tristis can often turn a grey/green colour. Campanella tristis doesn't have the sock, and the gills are more interveined, but both species can have a short greyish stem. In other species of Campanella the stem is usually absent. https://inaturalist.nz/observations/1064148