Lambsquarters or goosefoot (Chenopodium album) was regularly grown by the American Indians as pottage or a stewing vegetable. The European colonists would have readily recognized goosefoot as a Chenopodium several of which they also used as pottage.
In the peasant's garden, weeding had a strategy where inedible weeds were removed first but eatable ones were left to grow and harvested until space was needed for the main vegetable crop. Remember too, these are tough plants and can grow in soil that most garden vegetables will not and provide additional SHTF nourishment .