Make Your Own Buttons! One person commented about using plastic instead of cardboard for the base so they would be washable; be sure the edges are smooth though, so the yarn doesn't get cut by the plastic as garment is buttoned.
Chinese Waves Dishclothe by Margaret K. K. Radcliffe - "This pattern makes a nubby dishcloth, thicker and more stable than plain garter stitch. Chinese Waves is one of my favorite pattern stitches. I use it for edgings and for textured stripes interspersed with stockinette."