Fences are not permitted between our properties at the front of our houses. So my front garden runs right up to my neighbour's drive on one side. A few years ago I scattered a bunch of mixed seeds in the border between my lawn and his drive. He's barely been at home in the last year, so there hasn't been much movement over his drive. Now Forget-Me-Nots are coming up between the pavings. Presumably in previous years his car kept them down.
Neighbour says that they are from my flowers so I'm responsible for keeping his drive clear.
AIBU to think that he's a sandwich short of a picnic? After all, I've never complained to him about all the apple trees that sprout in my back garden from the apple trees in his back garden, and they are a heck of a lot more intrusive and harder work to get rid of.