Let's take another shot at this. I used this chart:
this Wikipedia page.
I tried much harder to make names that, while plausible, are not the names of prominent places. I mostly did this by doing Google and Wikipedia Searches. I may have missed some.
I want one name for each letter of the alphabet, mostly for mnemonic reasons (more on this soon). I also wanted variety in both sounds and geographic features, assuming some of these names would actually be placed on a map near features that match their name. I also tried to be careful about puns and awkward sounds, being aware that players and DM's will actually be saying these aloud to each other.
Eventually I think it would be cool to have a similar list for other languages/cultures, especially those that are more commonly associated with our psuedo-medieval worlds. So German, French, Italian-- maybe slavic languages next, even Hungarian, Spanish, Turkish, Arabic, Japanese.
The point is a small number of plausible names ready to go. If you can provide names from one of those languages have at it. In the mean time here's what I came up with:
Ashborough (fort among ash trees)
Brey (hill island)
Caerdon (hill fort)
Dunmouth (bay fort)
Exeley (clearing by water)
Finkirk (holy church)
Holmden (island hill)
Inverstead (at the mouth of a river)
Kelding (people of the spring)
Langbury (long, fortified enclosure)
Moss End (in a swamp)
Nancarden (ravine with stream and thicket)
Olchester (old fort)
Polshaw (wood by a lake)
Queensgate (on a road)
Rutleigh (woodland clearing)
Vale of Fearn (valley)
Whelworth (a mine)
EXeley-on-the-Wold (different Exeley by woods)
(Ashborough is there as a stand in for my own Fresno. There's a 75% chance they'll steal your wagon if you visit.)
Anyway, I'd love to see you come up with 26 names of your own. Maybe based on the area you live, your own constructed language, a different genre (like science fantasy or steam punk).