All liliy seed is white until they dry. If you harvest pods at "first crack", you will find the seeds next to the crack will be browning (and drying), but the seeds below will still be white and moist. When the pod is very spongy and hollow inside, the seeds are ripe enough to pick. If I do this, however, I do not open the pod until it splits on its own, which usually is not log after anyway. There may be some after-ripening going on in some species, although I don't think it has been documented. But it is well known in the closely related genus, Fritillaria.
