According to the companion planting bible, Carrots Love Tomatoes, chamomile increases wheat yields (plant 1 part chamomile to every 100 parts wheat). Bachelor Buttons (a flower) aids rye production when planted in a 1:100 ratio.
It should be noted that grains grow 3+ feet tall, and often require little water, so don't expect your companion plants to perform their best given this shaded, dry environment.
1,100 sq.ft. (about 1/40 of an acre) of land should yield 60lbs of organically grown wheat.
1,100 sq.ft. (or 1/40 of an acre) of land has yielded 50-150lbs of organically grown quinoa in the Cowichan Valley.
If you plant in the fall, the grain will get a head-start before the chilly winter hits. This may result in a stronger plant and therefore a better yield at harvest time (approx. 20%). You also might be able to harvest a few weeks earlier (e.g. July/August instead of August/September).
IMPORTANT: Note that some cereal grains simply won't survive cold winter temperatures (e.g. oats, quinoa, amaranth), so must be planted in the spring.