Formal but comfortable. Jeans are fine. Keep in mind this is an outdoor weeding on the grass, so maybe leave those stiletto heels at home!
Lord willing, end of June weather in Minnesota will be warm (mid 70s) and sunny! The evening might get a little cool so bring along a sweater or jacket just in case.
If your invitation says “and Guest,” then yes, if not, we would prefer if it was just you.