Whatever it is....it literally was not there YESTERDAY. How can anything grow that fast.
I was cleaning this very area yesterday up until mid afternoon and it wasn't there then.
There is ZERO chance I overlooked it. I actually left my pickeroon stuck in the stump one of these things grew on....so it would have been apparent. Also, the pure white color of it is what caught my eye this morning as I was walking up to the same spot to resume clearing out sticks and limbs.