A remarkable shelf fungus

I noticed it along the front path earlier in the week, and thought, 'oh, stimulated by the recent rain' and went on into the house. But it's kept getting bigger and bigger, and is impressively large for a shelf-fungus coming up from mulch. It's not unusual to see a large shelf fungus on the trunk of a declining tree, but not on the ground. I saw a similarly large one at the Garden today, at the base of a tree (hopefully coming up from the hardwood mulch and not from the tree).