Bisporella Citrina

My best guess is that this is Bisporella citrina or another similar species.










Bisporella citrina, or yellow fairy cups, is very common throughout the U.S.. It can be found spring and fall, and during the winter in warm places.
The individual mushrooms are very small, usually no more than a centimeter across, but they live in large, bright yellow colonies and are easily spotted. Look for them on fallen trees.

They are not classified as poisonous, but that's likely because nobody's ever bothered picking and eating the tiny things. I wouldn't advise being the first.

I got information from these sites:
http://www.rogersmushrooms.com/
http://www.mushroomexpert.com/bisporella_citrina.html