Tomato and cabbage
Tomatoes are repellent to diamondback moth caterpillars that chew large holes in cabbage leaves.
Gardeners have been planting garlic with roses for eons. Garlic helps to repel rose pests. Garlic chives are also repellent, and their small purple or white flowers look great in late spring.

Radish and spinach
Planting radishes among your spinach will draw leafminers away from the spinach. The damage the leafminers do to radish leaves doesn’t prevent the radishes from growing well underground.
Corn and beans

Cabbage and dill