Weird. Don't ask, but within ten minutes of opening my eyes this morning, I was like 'I wonder if the branches and general shrubbery is still where he (you) threw it.'
Call the city! Two can play at that game. This is right up @sean92008 's alley too.
Today - just today - the branches have been picked up and I assume tossed into the green can.
I saw the brother-in-law's car in the driveway, possibly he's the one who cut and threw them into my yard in the first place and they waited for him to come back over and take care of it. Just speculating. I realize now he's the one I've seen do major pruning, etc, over there in the past, cutting back the heavily overgrown hillside behind their house, etc.
I'm sure there was plenty of time spent tut-tutting their ill- mannered neighbor and the audacity of throwing that stuff back into their yard. People tend to side with friends and family when hearing such reports, if they truly didn't know how obnoxious that was, they still don't.