Around 1924, the Lancaster County Council adopted the honor society "The Pathfinders of the Golden Trail" or "PGT". On the pins and logos, they used the Greek Letters "Pi Gamma Tau". I'm lucky to have the two above pictured pins in my collection, most were destroyed when the group disbanded. The first pin is marked "1/10-10 KT" "Gold Filled". The second pin is marked "Sterling". They both have the same hallmark.

Read more about PGT here: 

http://usscouts.org/honorsociety/pathfinders.asp