thousandsofbolts.com has quite a few. Probably some other vendors do, too. Here are a couple I found scrolling through the "black" section, might be more in the "white/ivory" section. If you click on the "close up image" button, you get a 2" x 2" square so you can see the scale. Oh, a few of these might be ivory rather than white, check before buying!
http://www.thousandsofbolts.com/inde...oduct_ID=93916
http://www.thousandsofbolts.com/inde...oduct_ID=93915
http://www.thousandsofbolts.com/inde...oduct_ID=93911
http://www.thousandsofbolts.com/inde...oduct_ID=67489
http://www.thousandsofbolts.com/inde...oduct_ID=67490
http://www.thousandsofbolts.com/inde...oduct_ID=67496