If you actually planted sets ( the small dry bulbs)They tend to bolt rapidly. In the south used mostly as green onions. Plants in zone 8, also tend to bolt when planted in late winter or spring but not to the extent of sets. Short day onions winter grown are our main crop. Its harvest time.

The master gardener , Farmerdill, spoke.
The bottomline is that you cannot do anything about it.
Cutting the flower budd/stem may haelp a bit. Even then you are not going to get decent onions. My short experience tells me that they will rot soon. So, you should used them within a couple of months from harvest.

Thank you both. If it's not raining in the morning, I'll cut off the flower stem and see if they are ready to dig. I read one Q & A that said to leave them in the ground if they start to flower and they will multiply next year. True or false?

False, because in your climate they will rot. Next year, use seedlings instead of sets and you will get a much nicer crop.
You also can diversify into other onions, like multipliers, shallots and nest onions, which do well when handled as perpetual perennials.

Where do you get seedlings? All I've ever seen in stores are called sets - small bulb with short, green tops.

MARTI Google dixondale farms. They are in Texas.GOOD LUCK TO YA!!! YOPPER