Jill, there was/is a huge ranch in the Texas panhandle named the XIT Ranch. Stands for "Ten (counties) In Texas". Don't know if they would have had their own chips, but it's possible. If so, some of the chips could have migrated to Prescott where you found them?

See: http://www.utexas.edu/courses/mis311f/history/hist026.htm

It makes a good story, even if not true!