It took some looking but we found a car with an original mat.
Nick Taylor says:
Almost half way through this video it shows the trunk compartment of a
1960 Chrysler with carpet and the cardboard liner, spare tire with no cover. https://youtu.be/MTVlXXxva24
Randy Guyer sends this picture of his F trunk convertible before restoration.
And after restoration
(The spare tire cover may not have been used on the F.)
Nick Taylor writes:
A friend has a 1960 New Yorker that has 40,000 miles and a true survivor.
It had a battery explosion many years ago and was tucked away in a garage for decades.
Here are pictures of the trunk.
These photos are from Dave Mason of his 1960 Windsor.
It is not often we find one of these rubber mats in such nice condition.
2169672 molded into the mat