I'll go down to the garden where mine are tomorrow if it isn't raining, and take a photo for you. They come up with other perennials, and aren't particularly late. I know mine were sprouting a week ago when I was last in that garden.

They are now about 10 inches high, but a week ago they had this same look of having a + shape of 4 leaves from above, though the leaves are actually in pairs going alternately N-S and E-W going down the stems.

Your photos really helped a lot. I was able to cover mine with a piece of newspaper, while I tried to eradicate the offending grape-vine. Let's hope I can kill that sucker. It's mother vine is several inches thick and several feet long.

Glad to help.

For future reference, to kill something thickly woody like an old grape vine or a small tree or shrub, cut it to ground level. Get some Glysophate (generic Roundup) that hasn't been diluted. Use it undiluted (as for shrubs on the label) with a foam paint brush or a well-labeled squeeze bottle and thoroughly paint the part of the cut surface that is just under the bark where the tree's or vine's xylem and phloem/vascular system is. It may resprout a couple of times, though it doesn't always, but if it does just break off the sprouts and paint that surface with Glysophate. That way you avoid having to worry about overspray of herbicide, especially in a densely planted garden.