You will need:
1 1/2 yards per window of soft, 45" wide cotton fabric
Small handful of raffia
Tear the fabric and make the edges fray, for best results.
Drape fabric over rod, lightly gathering it away from the very edge of the window. If your window is wider, don't bother gathering.
Gather up the very center of curtain all the way up to the rod (as shown).
Fasten with a single strand of raffia.
Select remainder of raffia.
Thread through the first strand of raffia, tying into a single knot (not double). Let ends hang.
Use coordinating fabric for shelf scarves, doilies and table clothes.
Of course, fraying all the edges to add a unique touch.