Identify this mushroom?

[ciphergoth]

Jon called my attention to a curious mushroom he found in his plant pot today - "I don't recall that being there two days ago..."

Anyone know what it might be?

Also in random trivia:

• Party tonight, yay!
• Animals respond very differently than people to MDMA
• Respect to the toughest dude in the 'hood!
• Sign of the devil, dude! (thanks to reddragdiva)
• My ear still hurts. I whimper when the olive oil finds new corners to make itchy...