Hello,
I knew somebody would suggest H. deformis. These plants, however, do not
have two flat leaves. They have several leaves held similarly to H.
albiflos, slightly curved upwards/outwards, but not just the two flat leaves
as seen in pictures of H. deformis. I don't know if it makes a difference,
but I have two, and they have formed fairly large clumps. Each mature bulb
is about 3 1/2 inches diameter.