Blake Lenoir wrote: .... Have amaranth or pigweed and lamb quarter been used by all tribes before?
Hard to say how many different pre-Columbian peoples were using what level of domestication in these plants or relatives of them. Grain amaranth and Pigweed will be fairly closely related I suspect, as will lambsquarter and quinoa. And now all of them are grouped taxonomically within the 'Amaranth Family' [
https://en.wikipedia.org/wiki/Amaranthaceae ]. Just guessing then, but there possibly will be a continuum of ecotypes and species that were used either as a staple crop or as a survival food, depending on many ecological and cultural factors. Hoping others will jump in with more solid information.....