Lessee, amaranth is not a grass, it's more related to lamb's quarters (yes, the weed) than anything else I can think of. It cooks much like a "real" grain though.

Quinoa, I don't think is a grass, either.

Wild rice isn't a "real" rice, but is a grass.

All three are "New World" crops.

Does that help?

As to whether or not Corsair can tolerate them, I'd guess some very careful experimentation is in order. I'd take any excess quinoa off her hands if it doesn't work for her.