Alright, so I asked my wife's grandmother, Inara, (my "grandmother-in-law"? Is that a thing?) for some of her advice about creating a Latvian-themed setting, and I have a bit more information for you. Keep in mind that she was born in 1933 and fled Latvia after Russian and German occupations, and hasn't been back since coming to America, so she might be out of date for some of the more modern stuff. But she received a more-than-adequate education prior to the start of the war and while in the concentration camps. She still makes Latvian-patterned pillows regularly (I'm surprised that the craft store doesn't know my name by now with as many blank pillows I get there), and has a bunch of Latvian ornaments around the house.
Here's some (abbreviated) information I got from her:
The Latvian people are, historically, emigres from Asia. Tall, fair-haired and fair-eyed, but still with some Asian features (she specifically calls out clothing styles and the eye slant), they migrated down the Daugava River from Russia and settled in an area that was bountiful but relatively unpopulated. They have a markedly different language structure from their northern neighbors, the Estonians, who are more Nordic in genealogy. They settled and spread southward, into Lithuania and Prussia.
The Latvian midsummer festival of Jāņi got rolled into the Lutheran religion and is now called St. John's Day. It's a summer solstice festival whose details listed in Wikipedia fairly well match what Inara told me, so I think Wikipedia would be an adequate information resource for a fictionalized version of Latvia. (
en.wikipedia.org/wiki/J%C4%81%C5%86i ) She said that during this festival it was a common practice that a man and woman would jump over a bonfire while wearing the traditional wreaths, and this would mean they were now wed. (Perhaps there was more to this ceremony than that, but she didn't elaborate and I didn't think to ask.)
The patterns on the sashes and rug that randosaurus posted I can most definitely attest to being Latvian in design. The sashes in particular are extremely reminiscent of the patterns that Inara uses in her pillow-making. She showed me a collection of books she has from Latvia that also showed similar patterns. I have no ability to read Latvian, so I can't say what the books' contents are, other than the photos. The garb shown on the Latvian people in these books bear a resemblance to the black-and-white image randosaurus posted. The "recreated folk costume" didn't look Latvian, Inara said. It's possible that these costumes might be recreations of a much older style or a subsection of Latvian culture that Inara was unfamiliar with, or perhaps inaccurate. I wouldn't claim to know. She did say, however, that traditional Latvian jewelry uses a lot of silver and amber.
The Latvian climate, she said, is about like that of Canada. Long, cold winters and short summers. They grow a lot of grain--barley, oats, wheat, and the like--and vegetables. I think at some point she mentioned they had dairy cows and/or beef cattle on her estate that the staff cared for. The nobility and common folk had different foods if I remember some of her childhood stories correctly. I recall one instance where she, being very young, wanted to eat the "black bread" (probably a black rye) that the servants ate.
I tried probing her about traditional Latvian architecture, but didn't get much of anywhere. She remembered that they used to burn patterns on the doors of houses and barns to ward off evil spirits, and she showed me a picture of a Latvian chandelier, but that's about all I got. A quick internet search showed that old Latvian architecture was log cabin-style buildings with angled, earthen roofs. This matches what she told me about their climate, since, during winter, an angled roof is more likely to drop accumulated snow than to retain it, and thus is less likely to collapse from the weight of the snow.
A lot of the visual style--the candleholder we have at home, the patterns on the pillows and sashes--has a lot of X shapes, I noticed. Those and flowers, or stylized flowers.
In sum:
Your pseudo-Latvia has a culture that is a bit out of place from its neighbors, with different gods and traditions, since its people came from elsewhere. They have a distinct visual culture that seems both local and foreign. They have a nobility structure that resembles that of any other pseudo-European culture, except their nobility is a bit more hands-on, and less distant than others, due to their smaller population. More overseer than lofty lord.
The village folk live in log buildings with thatched roofs, farming grain and vegetables. They keep a good deal in storage for the long, bitter winters. Expect much rain during spring and fall, and don't expect the summer to linger past its due. Perhaps the people are, at the village level, a little distrustful of outsiders, since their nation has been conquered by others before, but they're a close community.
Theirs is a resilient nation, establishing independence after being conquered by other nations multiple times. Their productive land and access to sheltered waters is desirable to the more powerful bordering nations, but perhaps by virtue of nationalism driven by unique culture or just the distance to the centers of power of the powerful bordering nations, they maintain their independence.