There are common garden weeds which are not only edible, but are highly nutritious whether served in salad or cooked lightly as one would spinach. The trick is to learn to recognize them at all stages of their life--as tiny young plants or as flourishing adults. That's a young one is the pix above.
We live in southern Indiana, so I'm talking about my bioregion, which would include a lot of the Midwest (though maybe not the prairie areas). If you live in the Northwest, Southwest, your biogregion is no doubt quite a bit different. But if you're in most of the continental 48 states, then you could find lambsquarters in your garden, since it is common pretty much all across the country. Lambsquarters likes disturbed soil--as you find in gardens and other border areas where mankind lives. It grows in cities, in the country, and is one of those ubiquitious fellas who are found all over the place. Once you learn to identify them, you'll see them everywhere.
So check your garden! We're lucky to have lots of little lambys growing. I'm letting them get big enough to eat and then I'll pick them. But for now, they're welcome to grow. In former posts, I've written about lambsquarters here and here as well as lots of other places in this blog. Just look under the category lambsquarters. They are highly nutritious and tasty (not to mention, grow without any effort on your part and FREE).
A few days ago, I "weeded" our Amish friend's garden, which had a whole slew of lambsquarters. In fact, the LQ basically covered the area where they had planted celery! So I was lucky enough to pick all that. I processed it all by taking the leaves off the stems (edible but tough), then blanching or scalding them in boiling water, then drainging, cooling, and packaging them up for the freezer. So far I have 7 quarts in the freezer, with one more big batch of lambsquarters left to go. If you're lucky to find big areas of lambsquarters, do freeze them. They keep well and they're very welcome in the wintertime.
Purslane is another "weed" I let grow in the garden. I've talked about purslane in both the links I posted above for LQ. Also highly nutritious, purslane has the added benefit of being a great plant source of Omega-3. I like these as a salad green and we eat a lot of it in the summer. They don't freeze well, but you can pickle the stems. I haven't tried to dry it, but I might try that this year. You can find lots of pictures of purslane by going to Google Images and typing in purslane. That's what I do when I need to see a pix of a plant--very useful for identifying plants. It grows in gardens mostly--that's where I've seen most of it anyway. It's another plant that grows all over the country, north to south and east to west. It's very tasty and makes a really nice addition to salads. You can eat it as a potherb too, but I prefer it in salads. In Turkey, it's a national dish. Try it in a dish of browned ground beef, pork or lamb, rice, tomatoes and add a bunch of purslane. YUM.
The other of the three weeds I mentioned that I leave in the garden is woods sorrel. It's a light, lemony kind of plant. You can find a good pix of it, as well as other edible wild plants in this article of Wildman Steve Brill's. Check it out! This article includes mushrooms, berries, and a bunch of wild greens. I've written about woods sorrel here (among other plants). I find it in the garden all the time. And it is one of those I definitely leave til it's big enough to eat.
When it comes to weeds, if you can't beat 'em, eat 'em! These three, lambsquarters, purslane, and woods sorrel are all delicious and very good for you. If you keep an organic garden, as we do, then you don't have any worries about pesticides, herbicides, etc. Just wonderful, free food. As the world crashes down among us, these are good guys to keep your eyes open for. They'll help keep you alive and healthy.