There are a dizzying variety of mushrooms; so much so, in fact, that I'm hard pressed even with a field guide to identify most. This one is no exception. Looks to me like Lepiota procure. Can anyone confirm that?
Lepiota is a genus of gilled mushrooms in the family Agaricaceae. All Lepiota species are ground-dwelling saprotrophs with a preference for rich, calcareous soils. Basidiocarps (fruit bodies) are agaricoid with whitish spores, typically with scaly caps and a ring on the stipe. Around 400 species of Lepiota are currently recognized worldwide. Many species are poisonous, some lethally so." -- Wikipedia
One of the cliffs along the shore of the York River in York River State Park. The image above is looking left. The one below is looking to the right from the same position. All this is the result of the river's floods and tides.