Eat the weeds?

Can you eat weeds?  TPP has been asked this question several times during his long career, and that question has been thought about quite a bit.  First, the answer is that we do eat weeds, that is, some domesticated plants have their origins as weeds.  Second, a lot of these weeds have been around for a long time, so people have had ample time to domesticate them if they were thought to have any value.  Third, think about the difference between being edible and tasting good.  Here's the list of weeds that were presented as edible in an online article on Treehugger: wild amaranth, plantain, chickweed, mallow, curlydock, dandelion, purslane, clover flowers (warning: some clovers are toxic), lamb's quarters.  Now there are "grain" amaranths grown for their seeds, and even dandelions have some cultivars.  Generally selection is on extended juvenile stages, which in general are the more edible and better tasting.  If you grow lettuces and there are wild weedy species, lettuce begins to taste bitter as they bolt before flowering because the latex producing cells proliferate at this stage. 
Once years ago the Phactors tried New Zealand "spinach" because supposedly it stayed in an edible stage in the long days of summer and tasted like spinach.  What a good deal!  The plant is Tetragonia tetragonoides, and tasted more like freshly mowed grass than any plant we had ever grown.  It became pet rabbit fodder.  TPP thinks none of these weeds tastes good enough to be domesticated and if they had some redeeming qualities then people would have already domesticated them.  Otherwise TPP does not think these weeds will make up any significant part of any rational diet.  It may be good to know what is edible so that when society collapses, your friendly neighborhood botanist can earn his place in our new society.  Other than adding a bit of garnish to a mixed salad, a hoe is the best means of dealing with weeds. Mrs. Phactor found a recipe for "shrimp rampy" and it sounded reasonably good, but wild ramps while common enough in some places are not actually very weedy, and they do taste pretty good, as good as any oniony plant.  But foraging for an edible wild plant is different that eating the weeds.

Can I eat garlic mustard?

Yes, please eat it all.  Garlic mustard (Alliaria petiolata) is a horribly invasive weed. TPP must make the rounds of our estate two or three times a spring to keep the garlic mustard at bay; it invades from an un-kept preserve next door. It's a biennial taking two seasons to go from seed to seed. And, yes, especially when young the leaves are edible; they have a nice peppery garlicy flavor that would probably go quite well in wilted salad or in a pesto.  A young person asked about this.  They are fascinated with the idea of foraging for edibles. So, why not collect it and eat it?  Basically, it isn't that good that it's worth it.  Think about this. The plant is native to Europe where agriculture has been practiced for a few millenia.  The plant has long been collected as a culinary herb. The really good food plants have been domesticated and are grown at least in some places for food. But not garlic mustard. Our ancestors are telling us something, but by all means collect all the garlic mustard you want. TPP would recommend collecting along a section of a walking/biking trail built on an abandoned railway line. The banks of this trail abound (too weak), are a dense, weedy, morass of garlic mustard, and all these jogger/biker types zoom/zoom-zoom by thinking (?), isn't nature wonderful?  All the botanist sees is a mess of invasive weeds, and enough peppery, garlicy greens to choke the population of Chi-town.  
Understand TPP is not opposed to foraging.  Back in the poor graduate student days TPP foraged the country side for asparagus. Clumps grew along fences in the grassy margins of maize fields, so you could ride your bike along and harvest some spears returning home with a nice veggie for din-dins. The spears were hard to see in the tall grass, so TPP would bend a discarded can (all too common) over the fence to mark the spot when the asparagus shoots were tall and easily seen so you could find the young shoots next spring. This worked well until someone figured out the marking system and foraged earlier. So TPP does not intend to discourage foraging per se, but does have a thing about invasive plants and people's insensitivity to them. One friend says she can no longer walk in woods because she can't stop pulling garlic mustard or honeysuckle seedlings.  

Eat the weeds?

Generally TPP like the articles posted at Treehugger, but not this one on edible weeds so much.  The reasons are the usual ones: dubious advice.  OK here's the list of 9 weeds they recommend: dandelion, purslane, clover, lamb's quarters, plantain, chickweed, mallow, wild amaranth (pigweed), curly dock.  The best of the bunch are very young dandelion leaves, but they are better if you get the more upright growing meadow race rather than the very flat rosette lawn-mower selected race of lawns, but even then arugula and mustard greens are better.  Purslane, lamb's quarters, plantain (Plantago), chickweed, mallow, and pigweed are just sort of Ok you can eat them, but do you really want to?  Nothing much to write home about in this bunch except they are edible.  Curly dock has a lot of oxalic acid, and the article recommends changing the cooking water, and generally when that's required you are far better off getting some nice lightly wilted spinach and ditch the dock.  The picture along with the recommendation for clover shows Trifolium praetense, purple or red clover, but the article does not specify.  This is seldom a lawn weed (grows too tall); the more usual species is T. repens, and it and other species contain cyanogenic glycosides (they generate cyanide when eaten).  So this is just dubious advice without being more specific, and there are "clovers" in other genera too, e.g., Melilotus. At the end of the article, they beg off saying this isn't a field guide, but most of these have to be eaten at a juvenile stage, and most field guides focus on more mature flowering stages. Most amateurs aren't good enough to ID many plants in their juvenile stages. Here's an example from a couple of years ago - you pick out the edible wild carrot.  The images show you the problem, but hey, it might be your last mistake.  So basically TPP is never all that impressed by such advice as "eat the weeds".  Many of our leafy greens did start out as agricultural weeds, but they have been selected for better taste (less toxic) and more succulent tissues. Weeds - why bother?