Help to identify these?

[dave r]

I can't see any image I am afraid but the items commonly known as 'Cats Eyes' are usually the opercula of the Tapestry Turban shell, Torbo petholatus. Opercula (singular Operculum)are like a sort of 'trap door' the animal uses to close the aperture when it withdraws into the shell, it sort of seals the entrance making it hard for predators to get at the snail itself.
As to monetary value, very little, pennies each.
Here is an interesting link:
<!-- m --><a class="postlink" href="http://stoneplus.cst.cmich.edu/zoogems/catseyeop.html">http://stoneplus.cst.cmich.edu/zoogems/catseyeop.html</a><!-- m -->
Dave