I’ve been unable to find any ethnobotanical documentation that native americans used Trilliums (wakerobins) for food. They were rather considered as medicinal plants (see http://naeb.brit.org/uses/search/?string=trillium) and was also thought of as a poisonous plant by some tribes. The roots do however contain saponins. Nevertheless, it is used and considered to be edible (cooked as greens and used in mixed salads by modern day foragers) and this is also mentioned in some foraging books. It is a protected plant in some areas and I do not recommended to harvest it from the wild as it is vulnerable to overharvest as it takes many years to reach the flowering stage.. 
I  started collecting Trilliums as potentially interesting edimentals, and have eaten a few leaves (as reported the taste is a bit like sunflower seeds) and I use flowers to decorate salads. I would never be able to eat a lot of it anyway and wouldn’t do so either to be on the safe side and don’t recommend others do so either.

We’re now at the height of Trillium flowering season here, so here’s a few pictures taken on 1st June. Please let me know if you see any wrongly identified plants (there may well be hybrids in here!)