I knew there was a name for that flocking behavior. It's called "murmuration" and since you appear to be in Texas, it might well be they're flocking up to migrate north for the summer and come visit me in Pennsylvania, but that's only speculation on my part. They're not a welcome species, but it's too late now to do much about it. Here's an article if you'd like to check it out: https://pethelpful.com/wildlife/Amazing-Starlings-The-Good-the-Bad-the-Bold-and-the-Beautiful
Starlings. It looked like there were 10's of thousands of them, and the noise they made was quite unsettling
I find watching a large "cloud" of starlings to be a fascinating sight. There's sort of a "group mind" where the birds seem to change direction in mass.