See also Suomi, MN, named after the Finnish name for Finland.
And Balkan, KY, for the eponymous mountains.
Jersey City, New Jersey. The city, and indeed the State, are named after the island of Jersey. The State counts as “Some other region.”
Norfolk, Virginia. Named for the English county.
Thank you Peter.
I’m afraid I’ve been ignoring this list for the last few days, as I’ve been busy with the other list. I’ll get this updated today. I have other additions as well.
Any reaction on the fomat of the two lists: city list vs region list? I’m wondering which is easier to use/better looking/otherwise better? Or maybe some other organization? Looking for any feedback you have.
Cambria, California. Named for Wales.
They both seem fine to me, I kind of forget what each of them looks like after I’ve been working with the other one for a while.
By the way, I think but cannot yet confirm that Nordmore, ND is named for the district of Nordmøre in Norway. I’m guessing the same is true of Voss, ND and the Norwegian district of Voss.
Just looking at the ‘sandbox’ mentioned in the OP - a place called Avon would probably be named after any of the several River Avons in Britain - the former county of that name was only formed in the 1970s, and named after one of those rivers.
That’s an error by whoever wrote the Wikipage for Avon, Connecticut, wherein it says:
Thanks for the heads up.
The underwater ghost town of Pactola SD, named for the Pactolus River in ancient Greece.
Hecla SD, named for the Iceland volcano.
Calvary IL, and WI from the Biblical Calvary.
Ladoga, MI from Lake Ladoga in Russia.
Narenta, MI from the river Neretva in Bosnia/Herzegovina and Croatia.
Ulao, WI from the river Ulua in Honduras.
And Pacific, MO, Hayti, MO, Mexico, MO, Versailles, MO, Westphalia, MO, Mount Moriah, MO, Rhineland, MO, Carthage, MO, and Amazonia, MO.
There’s also Town and Country, MO, named after regions from all over the world. 
Fun fact: Rolla, MO was named after Raleigh, North Carolina, but they chose to spell it phonetically.
Have most of those, either from Missouri or another state. Of those I don’t have: Hayti has two derivations (I still may add it); Wikipedia says Amazonia has an obscure origin; and Mount Moriah is a biblical name with an unknown location. I got rid of all names in the last category, so it’s not going to be added.
BTW Missouri is a very fertile state for names on this list. Altenburg, Congo, Samoa, Klondike, Darien, Samos, Granada, Moselle, and Normandy are all in MO and already on the list.