How about this: take a couple of pieces of kraft paper and a scissors
out to your Excursion and do it yourself.  It shouldn't take more than
a few minutes to come up with a reasonably good pattern.

Then you could take another few minutes to measure them, create some
drawings based on the measurements (or even just shoot a digital photo
of your patterns or the finished mats, including a ruler) and put the
results on the web for other people to enjoy.