Agaricus - no common name

small group of white fungi; cap white smooth about 10 cm across with light brown center, specimen ranged from convex to flat and turned up on the edges as it gets older; pinkish brown attached crowed gills that look like they were veiled; stalk white straight ringed toward the top about 10 cm tall volva at base; growing out of the ground in a disturbed woodsy area, nice smell