Buttons are one of the first detail I look for in the things I buy. They are one of the items that can be easily switched with an inferior substitute as a cost-cutting measure. Companies that are looking into sustainable sources for buttons catch my eye. You would be surprised at the amount of detail that can go into a single button. A lot of the shirts I own have Corozo buttons sewn on them. Corozo uses tagua nuts in their buttons.
Corozo button on an Apolis chambray shirt
Corozo button on a Taylor Stitch gingham shirt
Bone button on a Barrett Alley Valerie bracelet