First class mail in a white envelope would not have tracking information - maybe the seller was mixing up the receipt number for tracking? Postage should have cost $0.70 or a bit more as the non-machineable rate. I would think the P.O. would have returned it to sender (as they threaten on their notice above the mail-slot within the Sun Valley post office here) or you would have been hit with a postage-due charge.

Wayne Casino chips were a tie-in to the Batman story. Bruce Wayne's father, Thomas, ran a casino (or several) in Gotham City, and some of the villains Bruce later tackles as Batman were no-good-niks that played or cheated in them. They came in a set, as I discovered when I found the green $25 Wayne at the San Diego flea market.

https://www.amazon.com/Batman-Wayne-Casino-Chips-set/dp/B005ENVI7C

Manufacturer is Gemaco.

The chips were first handed out at the San Diego ComicCon, one a day, per this article:

https://bleedingcool.com/comics/dc-comics-to-make-wayne-casino-chips-available-in-comic-stores/

Those four little thingypoos behind the numeral 1's represent Batman's cowl. So you better be good, Dick!