I know you can eat them. I'd have to imagine that the plant probably wasn't immensely important in the diet, as, when the
land was still in pristine condition, the range of this plant was actually far more restricted than it would be, today.
So, what kind of dye did it make? Red? Purple? All I know about that is the use of Red Puccoon
root for red & orange dyes, but that doesn't necessarily mean that they didn't use more than one plant for the same purpose, for reasons of seasonality, or even just liking slight variance in the color.