Those concentric chips are clay, and not particularly valuable to say the most about them. If you have a lot of them, break one to look inside. If you have just those, carve an edge off with a knife. I never liked the usual bakelite tests. Look here for some:
http://www.plasticfantastic.com/testing.html

Bakelite is a plastic (slick smooth insdes). It is often hard (for me anyway) to often tell one plastic from another, but it is easy to distinguish from a clay chip (granular insde like pottery).

(I'd sell one of the orange Baklite Corp advertising chips for $8 post-paid.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5039911525

Robt.