(Use Garden Combo inoculant - item #SIN-9400).
They can provide a trellis for other compost crops like vetch or field peas to grow up.
In zones where they winter kill, favas may be sown earlier so that by the time they freeze out, they have made some nitrogen, biomass, and a scaffold for hardy climbers like vetch.
While this is primarily a compost crop, these beans also make good eating and are so used in many parts of the world.
See also culinary favas under beans in the vegetable section.