Abbey of Down to Earth recently posted about her pink Rain Lilies; I told her I'd follow-up with how mine are looking so she could see the "bunch" into which her individual ones will hopefully grow!
Mine started out as six or less bulbs a few years back, and have even been moved a couple of times (usually leaving a straggler or two behind). Have never seen them develop seeds but they obviously produce additional bulbs.
My little patch was quite happy with the rain we had within the last week, and produced a nice collection of blooms. Some have faded, but some are still unopened - so the show should continue for at least the next few days.
I am no longer confident as to whether my Pink Rain Lilies are Zephyranthes rosea or if they are Zephyranthes grandiflora (if anyone knows how to definitively tell 'em apart, please let me know). But either way - they are nearly as much fun as a rainy day in central Texas!