Found this in Grandpa's Cache of Trinkets and Treasures: GC8VMQ5 while exploring Fort Langley in British Columbia, Canada.
Apparently Grampa has strict instructions to leave all the trinkets and treasures in the cache unless they are in the special tradeables container inside this ammo can. I found OFFICER MARSHA mixed in with those trinkets that were ordered to stay! Not sure how she ended up being imprisoned there, but I'm flaunting all authorities and setting her free to roam the world again.