What's this plant? Fern family doesn't flower...?

If I had to guess I'd say it is Darmera peltata, commonly called the umbrella plant. It needs a LOT of moisture, doing well along side water gardens, in marshy areas, and in woodland settings. It is native to the northern west coast of the US where it's found growing along stream banks.

It's a big plant, though it doesn't look it now. Once the very large leaves begin to emerge it can easily pass three to four feet in both height and width. There are some smaller varieties out there, like Darmera peltata 'Nana' which tops out at about two feet.