After the first rains of October, these enormous brilliant yellow Laetiporus fungi popped up here and there around Los Angeles. I remember seeing one growing on this same tree last fall, and there were dozens of them on a block near our house last year.
Apparently, they are edible, and according to this, they taste like chicken. (Note to my mother: I am NOT going to eat this.) It may be delicious, but in addition to "Chicken Fungus" and "Sulfur Shelf," another of its thoroughly unappetizing common names is "Quesadilla of the Woods."