Help identifying some handlebars.
 

After I got hit by a car and my Fuji-branded Nitto Olympiade bars got wrecked, I picked up some random randonneur bars for $4. They have a marking on them that says, "GB."

What are they? Are they anything decent?

GB was the major supplier of aluminum bicycling products (brake, handlebar stems, handlebars, etc) in the UK from the immediate post war years until some time in the 80s. GB stands for Gerry Burgess. Those handlebars likely came off a Raleigh or the like.

Certainly decent, and sometimes rather special. The nicer ones have fancy engraving, especially the ones made for Dawes, which have a floral engraving that goes almost to the bend. Purdy.

Yes, GB = Gerry Burgess. As long as they aren't damaged and fit your stem they should be fine.