I have seen this look quite a bit and did a little research to make sure I knew how to achieve it. For August, my stamp clubs got treated to this technique and some water-coloring too for these cards.
We used the Farmers Market designer series paper and Market Fresh stamp set that coordinates from the annual catalog (the big one).
Tip: Put dimensionals all around under the frame for a deeper inset look. I used 6 dimensionals on each card.