Wildlife Spotting

I can't really find anything like this in my guide books. Perhaps the closest I could get was the Pinwheel Marasmius, but I'm not convinced. It was about 1cm across the cap. It is gilled down the stem and has a central cap depression. It was growing on a dead, well-rotted log. My attempts at keying it out keep running into dead ends. It was located in Voyageurs National Park in northern Minnesota just below a ridgeline of a gorge in mostly red pine forest. Found in late August. Any help is appreciated.