What should my groom and groomsmen wear?

Your design sounds awesome! I love sunflowers at weddings, I think they're underrated.

First, decide whether you want to style the groomsmen to coordinate with the groom, or with the bridesmaids. My fiancée and I want the whole wedding party to match, so we can stand out. The guys are wearing classic tuxedos with accessories to match the bridesmaid's dresses. But for the record, I think navy would work just as well as burgundy!

I think grey suits with burgundy vests and burgundy ties/ bowties would look nice! Then you could get them sunflower boutonnieres.

Ah! Thank you for asking this - I definitely have a similar vision: burgundy, sunflowers, and the rustic barn/ fall feel! We're getting married in October.

Right now, we are leaning towards grey for the suits, with burgundy accessories to match the bridesmaid dress color. I think we might go simpler on the groomsmen's look so that my fiancé can stand out a little more.

Some friends of friends of mine just got married last month. Their wedding was outside at a popular state park, and then their reception was indoors at a rustic lodge. The groom wore a burgundy tux, and it looked great! Very fitting for what they were going for. I wasn't there (like I said, friends of friends), but I saw the pictures afterward. Now if you're having burgundy bridesmaid dresses, then that might be a bit much, but it might also look really good. I also think the navy blue would really work and not be too "out there".