Chicken of the Woods, Laetiporus sulphureus. I like to call this the 70 mph mushroom because it's probably the only mushroom you can positively identify while driving down the interstate. Compare this with its cousin, Laetiporus cincinnatus. It's sulcate with distinct zones on a brilliant orange cap. The underside is an even more brilliant yellow with about 3 pores per millimeter. As I mentioned in my post on L cincinnatus, morphology is dependent on conditions. L. sulphureus is usually described as growing shelf-like, but these are growing in a rosette. This is simply because they are growing on top rather than on the side of the log, a Shagbark Hickory, Carya ovata.
Note: These pictures appear washed out. It was much oranger in person.