Old Crock that tells story of post Civil War and secret societies

In Denton, Texas, the aftermath of the Civil War left turmoil among the survivors. Carpetbaggers had taken over the government; land was people 'taken' for non-payment of taxes; citizens decided they had to do something.
A man named Roark was making crocks--one of the few ways to preserve and transport food. Yankee troops were desperate to maintain control and did regular searches for goods, contraband, and plots against them.

This crock had a special mark on it. Looks sort of like a cover of a Rolling Stones album ( ha!)... But the mark meant that secret materials were stored in it.
The name Roark appears plainly. On the other side, an oval with a line running thru it ( looks like a mouth with a tongue sticking out!)
The crock ( like many things 150 years old) has some wear. A crack exists but it still could carry food or other items.