When I was in England in the late '70's I lived near the Portobello market and the first Saturday I was in one of the stalls and saw a small box with hundreds of the little MOP's for sale at a few pence each. I started to reach for them, when a "lady" standing over them, slapped my hand and said, "Off them, they're mine." I said "Do you collect gaming chips?" She looked at me as if I were daft and said, "They're for my kit." The stall person then told me as my puzzlement was obvious, that she and others would use the serrated ones to wrap their thread around. I managed to buy a few dozen; came home and at the first show I attended a dealer was asking $75 for one of the medium size ovals.