The True Cost of Food is a great 15-minute movie. This production by the Sierra Club is a great vehicle for understanding our food system. You can view the film online now.
And here is a great guide to eating on a limited budget.
Cooking that is kindest to the planet also yields the best-tasting food. Cooking sustainably means using fresh, in-season ingredients that have not traveled thousands of miles to your kitchen and preparing them simply so that their true flavor comes through. The sustainable kitchen includes a pantryful of unprocessed or lightly processed foods; the sustainable cook uses sustainably-raised foods from local suppliers.
You can find ideas for your congregations potlucks and a full curriculum on food called – Just Eating: Practicing Our Faith at the Table. You can download the reader and leader’s guide for free, or order them wholesale online.