Hard to say which it is Ann, there's a few which look much the same so an educated guess is the best I can do.
Hymenocallis littoralis looks a good contender, it has similar drooping tepals, has several flowers per stem and is a warm climate species. Is yours evergreen? Comparing the habit and length of the sepals as well as the size and shape of the corolla it seems to fit best but I can't be certain.
http://www.bulbsociety.org/GAL...
http://en.wikipedia.org/wiki/H...
http://www.pacificbulbsociety....
More on IBS..
http://www.bulbsociety.org/GAL...
It looks to be one which is commonly sold, along with H. x festalis ..
http://toptropicals.com/catalo...
