Food. Everyone's gotta eat, and the devil's in the detail.
In the country in which I set a few campaigns:
In the north and west, where the temperature dips, locals are fond of "Autumn Gold," a mulled spiced wine flavored with a bit of maple syrup. Favored meat: Beef.
In the south and east along the coast, lamb is the favored meat along with seafood, which is often stewed in this country. "Caffe" (coffee) and tomatoes are imported and popular among the coastal cities.
Alwyr Red (an imported cherry wine) is the favored vintage of the nobility; local brewers are known for "Sturngard Stout," named after the capital city.
Names.
I use Greek names in the east of the continent, Slavic in the northeast, German/Scandinavian in the northwest, Arabic and Egyptian in the southwest. In the more cosmopolitan areas, where Common is spoken, Latin names have become prevalent.
Nonhumans.
Elves don't have the same moral/societal taboos that humans do. Half elves are known as "Changelings" because of their suspect lineage.
Horses.
The home country is known for producing Destriers of surpassing quality. It is relatively easy to get a Large Warhorse with more hitpoints and slightly better ability scores. Not so for other types, though.
That's all that I can think of off the top of my head.