Depends on what you mean by "Garden standards". No, a single plant isn't worth harvesting by itself, and one square foot would be barely enough for a single ser

Depends on what you mean by "Garden standards". No, a single plant isn't worth harvesting by itself, and one square foot would be barely enough for a single serving, but a typical 1 acre lawn, imagine a square that's just ~200 feet/60 meters on a side, is 43 THOUSAND + 560 square feet. The linear/square relationship can be really surprising. Wheat yields like 50 bushels/acre, if I seeded my lawn in wheat I'd have 3,000 pounds, more than I could possibly hope to brew or drink. If I instead grew sweet corn, I'd have something like 15,000 ears. That's a lot of corn on the cob, and you've got to eat it within 24 hours of harvest for best flavor, and the harvest window is only a few weeks in early August. No, you're not going to want to grow cereals one stalk at a time in a raised bed, nor grow it like a little potted oregano on your kitchen window sill. But it doesn't take that much cultivation - say, 10 rows of sweet corn along the edge of the lawn - to get more than you can hope to consume.