Perhaps the most timeless gardening technique in history began with the Native Americans with the Three-Sisters Garden where Corn, Beans and Squash are grown together in a synergistic pairing. Yes, these sisters really get along! Corn is grown first, providing a future living trellis for the beans which are grown next (3-weeks later) and help fix nitrogen for the corn and squash. The squash can be planted the same time as the beans and provides a living mulch to guard against weeds and keep the soil moist for all.
Companion planting for fall is a great idea. If you have a tree that has lost it’s leaves try planting peas which are a nitrogen fixer at the base along with kale & radishes which will act as a trellis when they grow. If you don’t have a tree to trellis you can plant bush beans, lettuce greens, carrots & onions which will act as a nitrogen fixer & pest barrier.