What Mushroom is This?

[Xtuy]

Hello! 

Found these growing outside in a cluster and I wanted to identify them before they all disappeared. Any help will be greatly appreciated!

[vitog]

These look like thay belong to one of the Agaricus species, but more information is necessary for a positive ID: smell, spore print, staining, color of gills at different ages.  I'm not familiar with California species; you need guidance from someone who is.