When I first my got my Roadster, I pulled the seat cushions to give them a good scrubbing and found 2 original 3X spark plugs and the correct jack along with the remnants of the owner's manual. The cowl pocket had some papers that were so roach eaten I couldn't tell what they were.
While not Model A, I bought an unmolested '55 Olds some years ago.
Doing a cleanout of the car yielded a couple of condoms(still in the wrapper thankfully), Zippo lighter.
My '56 Pontiac had some 60s era nekkid girl photos under the back seat.
When I used to work for an exporter I'd find enough change in those old buses and semi's to cover my eats on the way home with some left over. I routinely found jewelry and other small trinkets in the buses, some of which were 14 or 24K gold.