David Weaver
If I had 20, i'd just start dealing them out. As of now, I think I have about 6, and two are "normal" and the rest oddballs.

Best place to look for them is ebay (if you can't look locally - I'm sure they show up for a few dollars at flea markets as they were super common stones - even my dad had one without knowing it).

Try for one that you can tell is a washita (earwax type color and look mottled in with some white, and if you can see across a corner in the pictures, they have sort of a waxy look at the edge) - and try for flat. I've learned to flatten them with a belt sander idler pretty quickly, but not much else is quick, and they smell like fiery death when flattening them.