Fomes fomentarius (Tinder Polypore, Hoof Fungus)
Photo was taken at Mazomanie Bottoms State Natural Area
Photo is taken in the Dells of Wisconsin River State Natural Area
Both photos (above & below) were taken at University of Wisconsin Arboretum, Madison

Photo was taken at Mauthe Lake Recreation Area, Kettle Moraine State Forest North
Photo was taken at Rock Lake State Natural Area