I found this at the Siskiyou Pass near the border of Oregon and California. It was in 2 pieces when I found it - that fit together. In this same area I found lots of petrified wood including petrified palm wood and other petrified wood both large and small. Could this be a petrified palm nut? The length of the 2 pieces together is over 15 centimeters and the diameter where it broke is over 6 centimeters.