http://plants.for9.net/edible-and-medicinal-plants/polygonum-polymorphum/
This is the closest I could see to it being recommended. It is also known as knotweed and is closely related to other knotweeds that are edible.
Doing a search for poisonous knot weed, I just find the oxalic acid concerns and that consuming very large quantities can lead to a person becoming very sensitive to the sun.
I might be willing to try a very small amount treated like Japanese knotweed, but I wouldn't be willing to test it on my nieces. Definitely a case of proceed with caution.
