Erik asked "how do they become warped?"

Here's how to warp a chip

Take one binder of chips
One car (rental car will work)
One Hot and Sunny Day in Las Vegas (June - August works best)

Take binder and stick in trunk of car. leave car in direct sunlight for 4 - 6 hours.
If the chips haven't warped take the chips out of the binder and shape them into any shape you would like. I've never done that, but I have heard stories about that happening.

Or you can just take a cup, fill it with water, microwave the water until the water is boiling. Take 1 chip (Not Chipco) and put the chip in a plastic bag. Stick bag in the boiling water for 1 - 2 minutes. Take out chip and bend it into any shape you like. If you're really lucky, you might just pop the inlays right out of the chip.

I have tried to unwarp a chip this way with good results...but not on a inlay chip and only on a chip that had little value.

I've been thinking of taking some of my old clay chips and seeing if I could make a coaster out of them by smashing them down until they are about 3 times their size

Good luck!