Bulbs are not commonly propagated from seeds because of the extended time between sowing and attaining a flowering-sized bulb.
However, many bulbs multiply naturally from seeds in the garden.
Also, plant breeders germinate seeds from hybrid crosses as is shown to the right for lily.
Lily seeds germinate to produce a small bulb with contractile roots that help pull the bulb below ground.
Lily seed germination. The arrow shows an emerging seedling that already shows a bulb shape.