An interesting species. I had not heard of it before either. While I enjoy some Lamb's Quarters mixed with other salad greens, I don't think I would prefer it alone. Likewise, it doesn't sound like the berries are really that tasty either. But, I really don't know. Perhaps its "unknown" status is well deserved.

Apparently wild in much of North America, including places in WI and MN. But being labelled invasive, I would not send caution out the door if you want to plant it. Sounds as though it might be something the bird would like (and spread). You may want (need) to net the berries from them.

I was thinking about trying some this year too, but I talked to someone on another board who had grown it and wasn't impressed with the greens or the berries. That, with what I've read about it's invasive tendancies made me decide against it.
If you decide to try it,please keep us posted as to how you like it.