Hi Barbara,
Welcome to the forum. I looked up your pudding pan in the blue book of Griswold and Wagner. I didn't find any value listed or any pictures, but I see that pudding pans were available in sizes 3, 4, 5 1/2,7 and 9 pints.I don't have the red book of Wagner and Griswold(yet). It might have some info. I'm sure one of our other members will check for you.
I also searched Ebay and got no hits.
I think it's safe to assume it was designed for making pudding. ;D No reason why you couldn't use it for other things though. Did you buy it to use, or are you a collector?
We have many members who like to use old cookware, as well as collectors. We all have fun talking about our old iron, and just about anything else too.
Take some time, and look around, I'm sure you will like it here.