I saw a news bulletin yesterday which said the world is down to a mere 10 week supply of wheat, lowest in 50 years. While the average homeowner does not have enough land to grow grain crops, we sure can grow many, many other nutritious crops. And not just summer crops either... veggies we can dry and store, like beans, or potatoes and winter squash we can keep in a cool spot under the house or a corner of the garage/basement.
Now more than ever in most of our lifetimes, we all need to heed your suggestions.
If a person doesn't have a yard at all (apartment dwellers), many cities have started community garden projects where they each get a plot of land to plant annual crops for their own consumption. And community canneries are becoming more frequent to store produce for later use, too. The fees for the use of each are very reasonable and much cheaper in the long run than buying from the grocery stores.
If growing your own fruits and veggies, you can also barter your extras for your neighbor's extras, sell at Farmer's Markets to recoup some of your investment, or make some extra cash.