Try Yuccado Nursery. They have an onlinie site with several different rainlily varieties for sale. They could probably answer you question abotu wanting to grow them indoors, too.

Xtal

i have some large pink ones . as for keeping it as ahouse plant they bloom when the low pressure systems move in and its a fairly warm time of year.they do naturalize well . im looking for other bulb tuber corms rhizomes. especially wanting tulip clusiana, t. saxatilis, t. sylvestris, but if you dont have any of that , tell me what you have . im a plant junky. oh i have the white rain lily too but it hasnt flowered yet

Kitten,
What did you find out? I have some white rain lilies, zephyranthes drummondii, both seed and bulb. They are drougtt tolreant once they get started. I do agree with the previous response is that it takes a barometric pressure drop from an approaching storm that makes them flower. It takes 3-4 years to go from seed to bulb to bloom. Nothing looks as pretty as seeing them bloom for the first time in the year when the temps and the rains collide. Their first flush of flowers is spectacular.

I know it's been a awhile, but I thought I'd check on ya.
Xtal