When the slab was poured, there was extra concrete (about a yard, apparently). The driver and our contractor pushed us pretty hard to find uses for it (lining the driveway ditch, filling the carpad, etc.). I guess it's a pain for them to get rid of it. If I'd known ahead of time we could have located a spot for a shed and had footers poured for it, but it wasn't a last second option. So I told them no thanks and take your concrete with you. Craig told me follow the concrete truck out and make sure he didn't just dump it in the woods, and I did, and he didn't.
Anyway, walking around the site yesterday we found this off the side of the driveway:
That is presumably what the concrete guy who poured the foundation walls did with his extra concrete (we weren't there for that pour). So the moral of the story is keep an eye on where your extra concrete ends up, and have a plan for it ahead of time if that makes sense for you.