I'm truly clueless as to what's growing in my front yard by my tree. An oak tree, I do believe... I find it rather attractive and would love to know what it is. I've searched but none of my search results seem to match.
Some sort of decay or disease fungus, possibly Armillaria (not definite, though). Not good news for the health or future longevity of the tree - it indicates decay, possibly severe, in the tree (and even worse, perhaps down into its roots). Best to have it examined by an ISA-registered arborist for safety issues.