Lilium nanum, and its variety flavidum regularly show up on rock garden society seed lists, such as NARGS or SRGC. It's well worth joining one of those societies if you're interested in them. You can browse past year's seed lists online. The seed exchanges happen in December and January. I've planted seeds once or twice, but have not brought any to flower. Mostly I am focused on growing the lower altitude Lilium, though, so I have not put much effort (yet) into L. nanum. NARGS https://www.nargs.org/ SRGC http://www.srgc.net/site/ Gordon