I also got to do the flowers for some friends' wedding this summer.
The sunflowers came from Cas of Mary Jane's Bakery. And each of the bride's bookclub friends brought flowers from their own gardens. There is a tobacco stake and rocks taken from Jacks Creek (to anchor the large bouquet) to represent the groom's childhood growing up on a tobacco farm there. Further, nothing grows without support--which is precisely what a wedding is about: the community committing to supporting the couple.
Yes, that is also a stalk of corn in the back. The bride never had a garden of her own until they started dating... a good sign, I think, for a marriage: the willingness to do hard work in order to harvest rewards. There is also honeysuckle from my house to symbolize how love can grow unbidden, invasively, a wild thing with a sweet aroma. I wish this for them, too.