There are several ways to decipher the codes left for us here. It could be code for a number if it is a letter or it could be a letter if it's a number, It could mean exactly what it is, It could mean what it looks like, or it could mean what the Spanish used that symbol for. We also have a Spanish Tobias cross used that has a number at it's base tied to it. Some Spanish symbols are also carved into the lead pieces which are not old enough to be Spanish. The K.G.C. and O.A.K. here were well schooled in the use of the Spanish treasure symbols and some combine Indian symbols, as well as the symbols of the secret societies they belonged to. It is all so mystifying to see and think about. There was a Spanish expedition though. "The Villasur expedition of 1720 was a Spanish military expedition intended to check the growing French influence on the Great Plains of central North America. Led by Lieutenant-General Pedro de Villasur, the expedition was attacked in present-day Nebraska by a Pawnee and Otoe force. Forty-six of the Spaniards and their Indian allies were killed. The survivors retreated to their base in New Mexico."
Thanks L.C. I thought the Spanish symbols you mentioned were probably on your dug artifacts. I've read of the Villasur expedition. There was an important east-west trail that went from the Great Lakes to the upper Rockies. It seems that every time the Spanish got close to that trail they were attacked. Another Spanish expedition was wiped out in that general area. Coronado went to the 40th latitude and explored the area before he returned to New Mexico. There was a place in north Kansas called El Quartelejo that the French used as an outpost for awhile. I believe it was used to scout anybody approaching that trail from the south.