Elfin Saddle

I have these (or a closely related species) in my front yard, just inside the north city limits of Seattle. They have shown up two winters running now, first appearing in December 2019, and they vanished with the big snowfall about a month later. They again appeared in December 2020; they're still there in early January 2021. They are under a relatively young conifer tree, but they are also on top of the roots of a boxwood hedge that died out (and the above-ground parts removed) about a decade ago.