Monterey used to be the capital of Baja and Alta California which was Mexico and a holiday celebrated by latin Americans is Dia de La Muerta which translates to day of the dead so that could be an artifact from when Mexico owned California.Just a little history of the area.On June 3rd mass was held under the oak trees and Monterey was founded and then in 1776 Spain named Monterey as the capital.In my opinion you should contact the historical society in Monterey and see if it has any historical significance and they can determine its age.If they were to want it back for a museum piece, I would just ask for recognition for finding it.