Buttons, buttons, buttons

Stiletto Girl Vintage has some incredible information about Mother of Pearl buttons; how they were made, what the environmental impact was, etc. I've collected them for years, being vaguely aware that new buttons might be environmentally risky, but if you click on the link to Stiletto Girl's site you can read all about the production of shell buttons in 19th century America. I've never learned so much from a blog...

These vintage buttons were bought in UK charity shops in the 1980s, so I don't know if they come from US sources or somewhere different.