I intend to share the contents of a few with you when I have time.
Three which look enticing are the Pears (yes as in the soap which I use, btw) Cyclopedia, Test Papers in General Knowledge, and Brush Up Your Manners. Guy Pocock wrote the one on manners, and he was the father of the famous author Tom Pocock. Guy had a long "brush up" series.
This is the exact edition I know have.....
I also picked up old arithmetic books which would cause blushes on modern teachers and a bunch of grammar books, mostly all in hardbound from the 1930s and from England.
Fun...and one more I might begin with is Walks and Climbs in Malta from 1944. Showell Styles, whose books on various subjects, including children's books, may be found on Amazon, wrote this one on Malta.