Definitely jeans and a blouse. If it's potluck it's not fancy! Also I think bootcut jeans can look sharper than straight leg depending on what they're worn with and the body type of the person wearing them. But then I'm from a place where "Dress Western" is a thing and includes cowboy boots and a hat.
I agree with leggings, boots, and a tunic style sweater/top. Or very dark, clean, well fitting boot cut jeans, with nicer (ie, not farm or paddock) boots. It sounds pretty low key. But disclaimer: Here in Colorado, jeans are appropriate for almost any occasion when done properly.
I'd probably wear a dress with leggings and boots. Tunic tops are not flattering on me. And I always feel under dressed at wedding stuff if I'm not wearing a dress.
Also, I was raised to wear a dress for most occasions.
Do you know anyone else going to the wedding? Check to see what they're wearing (you may notice across what to wear threads that this is always my suggestion!).
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