A trust box is untended roadside stand in which farmers sell their goods without being present. The trustbox uses the honor system for payment. There will usually be a box for buyers to slip in the posted amount. This particular stand sells local honey.
I paid special attention to this particular spot as I love honey (mmm, honey cookies!) and find the notion of trust one of the most attractive characteristics of rural tourism.
BTW, trust boxes are also something I have not yet seen in Latin America.