We planted this little maple tree in the backyard tonight. Last year our big maple tree out front had tons of helicopters (this year, none) and a couple of them started growing into trees. Several grew in the joints/cracks in the driveway. This one grew next to the sidewalk leading to the front door. We allowed it to grow there for a while, then transplanted it to a 12" pot, on our driveway, near the garage door, which is where we left it all winter. Maples must be pretty hearty, because it survived the winter and grew like crazy with all the rain we've had this month.
Here's another one growing in the bed out front. Some of the maple trees I've seen in our neighborhood did get helicopters on them this year. I don't know why ours didn't.