From Thomas Jefferson in the 18th century to the Southern Agrarians in the 20th, there's been a theoretical theme in political philosophy focusing on the small-farm-owning job-in-town citizen as a model for general admiration and emulation. As that concept now re-surfaces, in surprising strength, in the form of the suburban (for suburban-living preference in Vermont, see final paragraph)lawns-to-gardens movement, I'd add that there are five specific reasons for approval as well. In abbreviated form, here they are:
1. Grow-your-own takes open-land space. It bids fair to trump the "smart-growth" campaign pressure against low-density development.
2. Grow-your-own intensifies instincts for private property rights. Losing your own produce to a thief can swiftly undo a lot of mystical communal ideology.
3. Grow-your-own rewards producers differentially. Some folks are better at some things than others, no matter what the equal-outcome advocates may say.
4. Grow-your-own cultivates individual independence. Raising your own food won't fully eliminate the need for a cash income, but it helps marginally.
5. Grow-your-own demands recognition of the real cost of food in land, labor, and equipment. It might just dilute the urbanite-pleasing national-cheap-food-policy a little when former consumers learn what it takes to be a producer.
There are some minor ones as well, for example the 1998 Steven Blank book, half prediction, half desire, with a self-explanatory title: "The End of Agriculture in the American Portfolio". Its basic thesis is that Americans are too smart to spend their valuable time growing stuff, when they could be in their labs and offices inventing and communicating, while loin-cloth-clad folks elsewhere can ship us whatever we desire, at suitably low cost. Whether his argument has official approval (he was a USDA staffer while writing) is a debatable point; what's non-debatable is that suburban gardeners disagree.
More recently, the USDA has again acted in ways interpreted as hostile by the grow-your-own movement, this time by orchestrating the "Food Safety Modernization Act", H.R. 875, which requires governmental tracking of food-item production and commerce, down to the front-lawn veggie patch, ostensibly in the public-health interest, but arguably (note that Monsanto is an advocate of the proposed regulation) a concealed effort to prevent loss of commerce to the existing (and at financial risk) beyond-the-farmgate network of handlers, processors, distributors, and retailers. It's a strategy which has fairly deep historical roots, as those who have followed the retail food industry's (mostly successful) efforts to ban producer sales of raw milk have seen; I can recall attending Health Department hearings in the '70's where industry lobbyists spoke piously of the need to keep all milk in commercial channels for the public welfare. Now the same industry/government concerns are being voiced with regard to the pressing need for regulation of farmers' markets and, indeed, all producer-to-consumer food sales, presumably as an essential protection against mad cows and terrorists. The USDA might respond, in self-defense, that it has published a whole series of books and sponsored conferences on backyard gardening, as, indeed, it has.