(happily growing in my garden this year)
Anyone familiar with gardening in my neck of the woods has seen it and probably yanked it out or mulched over it. It spontaneously generates wherever the soil has been disturbed. It's new growth tends to have a powdery green color much like the powdery look of blueberries in the southern heat. The stem may get purple streaks as the plant gets older. The plant is very distinctive lacks any local lookalikes.
Up until the past year I was ignorantly yanking, trampling and cursing this plant. It was growing in my garden where I wanted my veggies to grow, it was growing in my pastures where I wanted grass to grow.
I wish I could remember which issue exactly but some time in 2010 South Carolina Wildlife Magazine featured an article with Rudy Mancke's daughter on foraging. Along with discussing the fruit of Maypops/Passion flower vine which I had always known were edible it discussed Lamb's Quarters. They wrote that it is perfect spinach substitute. There is no taste to aquire for it. If you like spinach you will like this equally well.
So this spring not only have I not yanked Lamb's Quarters up, I have carefully avoided trampling them. I sampled them raw earlier in the season. They were very mild though not quite as wet or strongly flavored as spinach. Even the kids (Isaac, Alyssa and Katie) ate the leaves. I think the kids were eating them only because the idea of eating weeds directly out of the yard was an idea too good to pass on.
Monday, I gathered a substantial enough quantity of Lamb's Quarters to be worth cooking in a pan. I melted a pat of butter and then tossed the leaves in to wilt the same as I would cook spinach. The result? It was DELISH. Tasted and looked just like spinach. Maybe a hint nuttier. If someone had handed me both on plate I probably would not have been able to tell the difference. Why not just grow spinach? I have planted spinach but the Lamb's Quarters grows much better and does well in the heat when the spinach is miserable sickly. While the bugs will chew it, its prolific enough that there is enough to share and no need for pesticides.
Here is the nutritional analysis.