The 9 is the shape of the key. Seem an unusual shape for a key. Don't have any padlock reference books, but based the WBCo and the keyhole shape would look in that direction.
Here's the answer I got from Wilson Bohannan regarding the lock:
Hi Dave!
I believe it is a Wilson Bohannan lock. WB listed the Company information on the shackle part of the lock that I guess you didn't find. I would say by the logo layout that the lock is before the Company moved to Marion, Ohio in 1927. We have gotten inquiries from people who have found the WB locks metal detecting like you in various places over the years.