The incense is nopal, the resin from small trees much like frankincense. I know it grows in the dry interior valleys of Quiche and Baja Verapaz. A common crossover religious practice I saw almost everyday is the tradition of maintaining crosses at the tops of rises of foot trails, the cuesta. You would stop at these places for a little break and there would always be little flowers, pebbles, etc. scattered around the cross. In the villages of Chimaltenango there was an annual blessing of the seed corn at the Catholic church. The women would decorate a basket of their finest ears of corn, parade to the church, and the priest would bless it. You can't tell me that wasn't an ancient tradition.