Once they send up flower stalks, forget about mature onions. They make good "green" onions. Walla Walla is not available as sets. Did you mean plants? Yellow sets are almost always Stuttgarter or Ebenezer.

They aren't trying to bulb, they're trying to flower.

I could use the space they are in, so if the crop has failed, I will pull them ASAP.

Might as well clean them out and use the space for something else as you won't get anything edible out of them now. Wrong planting time, too wet soil, and very possibly the wrong variety for your location since you need long day varieties only.

As already mentioned, Walla Walla doesn't come in sets, just plants. So they were most likely something else all together.

Dave

I bought the sets as an after thought last fall at a good established nursery. I assumed they were the correct variety for this area.

Let's assume that they were long day varieties...any opinions on why this happened?

Sets planted in the fall make good early spring grenn onions/scallions. However because they are long day, they need the summer soltice to bulb. Onions are biennials, because they overwintered, they are programmed to seed. Short day onions (where climate permits) are planted in the fall and are triggered to bulb by the spring equinox.