Grackles, the [censored]-roach of the bird world. (although those may be crows? Can't tell)
I don't think they are big enough to be crows. Yes, grackles are what you say but they sure can clean up the frys and whatnot from the walmart parking lot. Used to work with a guy that was a real prankster. He would toss bird seed in the back of co-workers trucks sometimes. Those grackles would send a fellar straight to the car wash.