Mystery compost heap neighbour

Trouble in the compost heap? Mine seems to be full of fruit flies and sprouts this week, but it doesn't appear to be turning things into compost very quickly these days. I blame it on the cold and drizzly weather, but I secretly wonder if something's gone wrong. Maybe it needs a good aerating mixing.

I must've done something right in the past though, since the whole area around the heap is a lush, dense sea of these leaves growing 6" off the ground. No flowers that I can see. I wonder what they are.

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Edit: Preliminary guess due to a complete fluke while browsing OntarioWeeds.com is that it’s Anemone canadensis, so it should be flowering soon.