You can never go wrong with Greyhawk

In addition to the stuff you've already mentioned, there are some knightly orders active in Furyondy too: the Knights of the Hart have an order there (and IIRC one of the Castles in that boxed sets was for them).
And there's also old lore dating from Ferrond, when Dyvers was the imperial capital for that region of the Great Kingdom before the empire fell.
Some other resources if you're interested:
- Jason Zavoda's index at https://www.facebook.com/groups/Greyhaw ... ces/files/ (for digging up references to canon you may want to use, check out, or hack)
- Greyhawk wiki at https://greyhawkonline.com/greyhawkwiki/Main_Page (this version includes entries for all of Jason Zavoda's index work too)
- Anna Meye's 576 CY maps at https://www.annabmeyer.com/576cy-download/ (I prefer Darlene's style, so YMMV, but she's very good at zooming into greater detail, as well as incorporating sources across eras that you can then use/discard as desired)
- other fun resource I like on my site at https://www.greyhawkonline.com/grodog/gh_links.html
Allan.