Petasites japonicus. Jumbo leaves on long stalks to follow. Spreading rootstock forms patches on damp ground.

Yes! Thank you!

Spreading patches is IME here in NH a restrained description of this plant’s desire to claim territory. There is a patch at UNH that is huge, restrained only by mowing, masonry, and swift running water. Consider whether this is a battle you want to take on.

Given that essentially nothing other than moss grows in this particular part of the yard it's probably a good spot for something tough and aggressive!