According to Jocelyn Howells button book “Button Materials from A to Z” these are fairly scarce buttons they are a type of porcelain with designs that resemble some china buttons, they have a cemented-in metal loop shank.
In her book she asks if anyone can identify the manufacturer and are they vintage or antique?
Jocelyn is the author of three books about identifying button materials, including two on synthetic polymers exclusively, based on more than 10 years of intense research and study.
Read more at her website http://mysite.ncnetwork.net/buttonjoss
or contact her at email@example.com
Her books are a must have for button collectors