Hi Lwood 114,
The majority of these birds look like Common Grackles to my eye. Upon looking closely at the photo, many/all of these birds look long, slender bodied with a very long tail, both of which point to Common Grackle. Red-winged Blackbird would be slightly smaller and stockier with a noticeably shorter tail. Same goes to European Starling, upon which these field marks of shape would be even more exaggerated. I also echo what birdboybowley says about the formation of starling flocks; they are usually very tight and turn in formation. Being in Tennessee, the expected species to make up a large blackbird flock would be European Starling, Common Grackle, Brown-headed Cowbird, and Red-winged Blackbird. Other species, such as Rusty Blackbirds, American Robin, and (if you're really lucky) Brewer's Blackbirds would occasionally mix in. Chances are, in as large a flock of grackles as this, there were probably at least a few Red-winged Blackbirds mixed in, although I couldn't pick any out of the photo at first glance. These two species commonly associate.