Not sure about "companions,"
Check out Back to the Basics.
planting is based around the idea that certain plants can benefit
others when planted next to, or close to one another.
Companion planting exists to benefit certain plants by giving them pest
control, naturally without the need to use chemicals, and in some cases
they can give a higher crop yield
Check out Mary's Top 10 Crops with Companion varieties!
chamomile with onions improves their flavor. Other companions are
carrot, leek, beets, strawberries, brassicas, dill, lettuce and
tomatoes. Intercropping onions and leeks with your carrots confuses the
carrot and onion flies