I doubt it. The Lamb's Quarter has a slight lemon taste to it. We had a clover like plant that had a delightful sour taste. We never ate pigweed.We have purslane too. My daughter picks some when she visits, and uses it in salads. She also gathers wild carrot and wild onions. I'm sure she will want some pigweed.
I wonder is it is what we call Sourweed? We used to chew that as kids. If it wasn't too mature, it had a sweet taste, not a sour one.