Can anyone help me identify this mushroom? Batches of them erupt from the ground after a rain in a relatively open area (that is, not smack-dab under the trees but with only indirect sun anyway). They hang out a few days looking like this and then turn into an oily black mass before decaying back down to nothing.

This is a wooded area (Ponderosa pine, incense cedar, oaks) at 2,600' in Calif. The zone ID here is from The USDA Hardiness Zone Finder (found at http://www.garden.org/zipzone/index.php), although I'm sure there are microzones.

This is my first posting here and I'm not sure how to include photos. I've put four photos up in Picassa, link provided below.

I appreciate any insight! This seems to happen every November. We bought the property four years ago.

Here is a link that might be useful: Photos (Picassa album)