The Indians made maximum use of land with the "Three Sisters."A rule of thumb I have always seen is 1-2 acres per person needs to produce for a year's worth of food. A back yard with 1/10 of an acre a couple and then two kids like most suburban homes...isn't going to swing it.
Corn, pole beans that climbed the corn stalk, and squash to outcompete weeds around the base of the corn stalk. Three different plants in the same space that one normally needed.
Plus, the three combined provided balanced nutrition.