Bakelite Button - identify by run hot water over it/or rub with finger then smell it. If smell Formaldehyde or Cod Liver Oil or have a sweet chemical smell. Another way is to put a bit of Simichrome Metal Polish or 409 All Purpose Cleaner on a Q-tip and rub it on the button. If the Q-tip turns yellow, the button is made from Bakelite
I SO want to do this now. This would be so cool hanging outside as a 'windchime' kinda thing!
Vintage green Bakelite and mother of pearl heart buttons
BAKELITE Vintage Sewing Buttons