Dave,
I can't explain the ashtray, but I agree with James that it looks like the Harvey's ashtray was stuck into another one. I have the Harvey's 'tray and it's the kind of rounded square shape that shows up in your scan. James probably has it too, and it's been on ebay a dozen times.

When I was a little girl, and asked "But WHYYYYY?", a frequent response was "to make little girls ask questions!" So why was the 'tray made?? To make flea market shoppers ask questions! Enjoy your weather...we've had about 8-10 inches of snow since we got back from Las Vegas, and more on the way!