You'll neew two pieces of fabric aproximately 2 1/2 x 8 inches, a pretty button, and some ribbon.
Sew the two pieces of fabric together so that they're one square. You won't be stuffing anything, so just sew this all the way around with the pattern side facing out on both sides.
Fold your rectangle into three approximately equal sections. Fold in the right side over what will be the bottom, and fold the left side in over that. Sew along these folds so that they'll stay put.
Make your ribbon into a loop big enough to go over your button and sew it onto the fold that holds together the "bottom" flap and the middle flap. Then sew the button onto the top flap so the loop is able to go over it so it can close.
Tah Dah! I also sewed the ribbon along the outside just to be pretty.
I put a little pocket on the right side as well.