why is my collard growing flowers?

Answer 1

Sounds as though it's "bolting".
You can try chopping the flowers down, but if they grow back, consider replacing the plants altogether.

Answer 2

If you are speaking of collard greens then the plants are getting ready to go to seed. The weather is too warm or the plants are just too old.
They like most green leafy veggies like cool weather.
Cut them back and let them re-sprout.
Good Luck!

Answer 3

All "greens" produce seeds when they are mature (old). So collard, lettuce, Chinese cabbage will all produce seeds if left in the ground too long.