Yep, in their second year that is the onion's mission to make seed to propagate the species. You can cut these flowers off and chop them up and toss them in the soup. Will they make bulbs? I don't know. Remember the whole onion plant is edible and you can take it at any time.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-