Disclaimer: This writeup is meant to describe and discuss a common plant, but may not contain enough information to properly discern edible from poisonous plants! Please do not go around eating wild plants without a reliable guide to edible plants, complete with lots of pictures and illustrations. I'd recommend Identifying and Harvesting Edible and Medicinal Plants in Wild (and Not So Wild) Places by Wildman Steve Brill. So, without further ado:
The Plant Itself
Chenopodium album, a common weed, found in disturbed earth in the Northeast United States. Along with Quinoa and Epazote, it is a Member of Goosefoot family, also called White Goosefoot, Pigweed, Fat Hen and Wild Spinach. Its scientific name indicates that it is a variety of Goosefoot, but Lamb's Quarters is the subject of taxonomic debate among botanists, over whether it is different enough to deserve its own species. It's an annual plant, so it dies off every winter.
Uses
Leaves can be eaten raw in salad, or any other way you would use spinach. The flavor is mild, and makes a good addition to soups and other dishes with a lot of flavor, with the intention of adding some extra vitamins and minerals. Seeds can be ground up to make a flour, and boiled into gruel. It has no medicinal value to speak of, but is particulary rich in vitamin C, calcium and vitamin A, not so rich in iron or potassium as spinach is.
Foragers in the Northeast love this plant for its similarity to spinach in useage. The leaves are a major food source for the white-tailed deer, and the preferred nesting ground of Painted Lady and Silver-spotted Skipper butterflies, and other moths and butterflies, depending on location. The seeds are eaten by birds, especially sparrows, and small forest mammals (chipmunks, squirrels, fieldmice, voles).
Identification
The leaves have one main lobe and larger leaves may have two smaller lobes on either side. Leaves are very slightly jagged or toothy and on average, about as long as a thumb. Foliage is green or slightly greyish, but new leaves or all the leaves on the young plant may be covered with fine white hairs. Tiny waxy green flowers emerge from the central stalk, which is succulent and may be streaked with dark red lines.
Location
Lamb's Quarters prefers earth rich in nitrogen, and like many edible wild herbs, its favorite place to grow is an organic farm bed. Many organic farms will pay in vegetables anyone willing to weed out their beds, a terrific deal for someone who plans to take the weeds home to the table as well. Other than farms, Lamb's Quarters can be found in open fields, lawns, gardens, wasteland, and alongside construction sites and paved/roadside areas.
http://www.indianspringherbs.com/lambsquarters2.htm
http://en.wikipedia.org/wiki/Lamb%27s_quarters
http://www.illinoiswildflowers.info/weeds/plants/lamb_quarters.htm
http://www.fcps.edu/StratfordLandingES/Ecology/mpages/lambs_quarters.htm