I should have completed a description. It's about 1/2-inch in diameter. It's papery and almost translucent around the center seed. It is a very pale tan/cream in color. (I took the photo against a bright pink nursery container so it would show up.) These seeds appear everywhere in my front and back yard...under trees, on the patio, in the lawn, floating on the pond... I hope they don't mate with the maple propellers.
It looks like elm seeds. They fall just now by the zillions. I dont have a tree but my neighbor does. Next come the zillions of sprouts. They have oval leaves with saw-tooth edges. Once they get about 10 inches high, they are very hard to pull up. The root thickens into a carrot-like thing about 2 inches below the soil.
Thank you! I've been pulling sprouts just like the ones you described, and you're right about how hard they are to pull when they grow taller. I just don't see any full grown elms in our area, though. They must blow in from quite a distance. Thanks again for the ID.