Ideas for Faux Wild flowers?

I love the idea of a bright, wildflower themed wedding but I'm getting married in March in New England and I'm not sure how much would be available from a florist, plus I don't really want to spend that much on flowers. Our centerpieces are covered by our venue, so I just need items for the ceremony (bouquets, boutanires, etc). I'm looking at Something Borrowed Blooms, since they have flowers that fit what I'm looking for, but I'm okay DIYing bouquets myself, but I'm not sure where to look. I've looked at Sola and Ling's Moment, but haven't seen much for a wildflower theme.

Any ideas of where to find flowers to DIY?