I do this each year with my Alliums , there are several Alliums which produce the bulbils .I sow them as Berghill says but I add a handfull of grit .. The bulbils will turn a dark brown towards Autumn .Just put a bit off grit on top too and put them outside. Then forget about them they do take a while but its worth the wait. If you have the room sink the whole pot in the ground leaving about an inch showing . Some Alliums have the seed too . I tried that last year but they were hard to get out wont bother a second time- stick with the bulbils.
If you like lilies there is an orange lily which has the bulbils at each leaf joint, I set these in the same way and they germinate the year after .
Sorry cant think of the name off the lilly .