Beware the imposters.
Many don't understand that seed from Lilium martagon var. album doesn't usually yield Lilium martagon var. album seedlings. Usually, this is because the grower has only one white martagon plant and assumes it will breed true.
NOT true.
Even if there is another different Lilium martagon var. album plant among the other martagons, wouldn't one get true L. martagon var. album seeds?
NOT true, again.
To get true L. martagon var. album seed, one must make sure that pollination occurs ONLY from an L. martagon var. album plant. The flower must be protected from contamination of pollen from colored martagon flowers.
Fortunately, there is an easy way to tell if you have true album seed. Lilium martagon var. album seed is very light tan.
Left - (regular) Lilium martagon seed
Right - Lilium martagon var. album seed
Edit: I have since learned that, yes, all L. martagon album seed are very light colored, but not all very light colored martagon seed are necessarily L. martagon album. These "anomalies" do always possess white or light colored flowers, however.