This is a suggestion for one pattern, but it's easy to experiment with different patterns you create yourself. Straw is relatively inexpensive and easy to cut; if you make a mistake, simply remove that piece and just redo the area.
Resources: Frames are available from Pearl Fine Art Supplies. Straw from France's BDF-Douineau. In the United States, straw is available from the Straw Shop (email firstname.lastname@example.org) or A Touch of Kansas (email email@example.com).