Growing wheat in your backyard garden for personal consumption is illegal. Based on the Supreme Court decision in Wickard v. Filburn, "Congress can regulate purely intrastate activity that is not itself "commercial," i.e., not produced for sale, if it concludes that failure to regulate that class of activity would undercut the regulation of the interstate market in that commodity."
"Filburn was a small farmer in Ohio. He was given a wheat acreage allotment of 11.1 acres under a Department of Agriculture directive which authorized the government to set production quotas for wheat. Filburn harvested nearly 12 acres of wheat above his allotment. He claimed that he wanted the wheat for use on his farm, including feed for his poultry and livestock. Fiburn was penalized. He argued that the excess wheat was unrelated to commerce since he grew it for his own use.
According to Filburn, the act regulated production and consumption, which are local in character. The rule laid down by Justice Jackson is that even if an activity is local and not regarded as commerce, "it may still, whatever its nature, be reached by Congress if it exerts a substantial economic effect on interstate commerce, and this irrespective of whether such effect is what might at some earlier time have been defined as 'direct' or 'indirect.'" www.oyez.com
By enacting the legislation Congress set forth controls to protect commodity wheat pricing. The Supreme Court (in 1942) upheld the laws agreeing that allowing Filburn to produce wheat for private use did indeed present a threat to the supply be reducing demand in the open market.
Growing a small plot of wheat in your backyard, while not in itself a threat to overall supply, could be regarded as a dangerous practice should it become commonplace. If, for instance, millions of Americans suddenly began planting wheat for home use, the Federal Government would have the power to step in and eliminate or control its cultivation.
The Supreme Court recently upheld the government's claim that growing and cultivating marijuana for private medical use did indeed violate laws regulating the production of commodity products and was within its Federal powers because the introduction of locally grown medical pot has an adverse effect on the entire market.
It would seem to me that the Government is somehow legitimizing large scale marijuana production and in limiting the cultivation of medical marijuana, it is protecting the street price of pot. I guess it's comforting to know that patients with a medically diagnosed condition for which marijuana can offer relief, can sleep soundly now knowing that cultivation, distribution and sale of marijuana is back in the hands of big, foreign drug cartels.