I have a lab who ate everything when he was a pup (clematis, ivy, and something that made him really sick) but only eats grass now, as far as plants go, anyway!. I keep plants that are really poisonous (oleander) in the front where he doesn't have access, just for my peace of mind. I looked up rain lily (zephrantes?)along with poison on Google and couldn't find anything, except your post. Usually if a plant is dangerously poisonous, something comes up. You could try posting on the pet forum.