Sorry I missed out on those, they would have been fun for me and some of the vets I mentor to play with.
Some ideas (and some may be repeated from above) are;
Yoyos for sure.
Pen stands in a dome shape using
these type of inserts
Sliced thinner I think these can be turned into pendants, fill the hole with a stone or button or?
Use two similar pieces, sliced in half and you'll have wheels for a psychedelic wood toy car, gotta paint the car to go with the wheels of course.
With a hardwood dowel insert the could be turned into spinning tops
stack three and turn into a snowman
can the thicker pieces be used for kalidascopes?
I like the ring holders above
cut in half so its like a half circle, then shaped into a drawer pull?
Open the hole, slightly flatten a spot on the side and put in a 1" or 2" clock insert
I'll keep pondering.....