Third image appears to show something of a volva at the end of the stipe. This together with the pinkish and possibly free gills suggests what I used to know as Volvariella speciosa but its had a few name changes since then.
The membranous patches sticking to the cap would be remnants of the universal veil that is wrapped around the entire mushroom at the button stage and which breaks (and falls away from the cap) as the mushroom expands.