I live in Texas, about a 30min drive from Galveston. My girlfriend came home and said she saw some red birds flying over, and didn't think Northern cardinals flew in packs. I told her that I didn't think they flew in groups since they were year-round birds here. About 10-15mins later, we decided to go outside and see if we could find any more of these groups of red birds flying over. As soon as we walked outside, there were hundreds of them, flying pretty spread apart. They came in groups of about 20 or so. One group after the other. All of them were flying in the direction of Galveston.
Her binoculars have a little more reach than the DA*300, so we went for those. The birds were far enough up that we couldn't see detail, but could see colors and shape very well. I would guess around the size of a cardinal, possibly slightly larger. We both saw a red breast (it could have been a vibrant orange), green under-wings, and a prominent white-ish beak. These birds were flying where the sun was to our back, so they were lit by the sun. No silhouettes here.
Painted Bunting is the closest I can find, and the Merlin bird app says they don't have a bird that matches.
Any other guesses?