They're not inside plants - and they would drop and sprout around the parent plant naturally had you not harvested them. I'd just scratch the surface of the ground a little and drop them in where you want them and cover them over lightly. They should be totally hardy in your zone - especially if they're the spotted Lilium Tigrinum. Mark the spot where you put them so you don't accidentally pull out the grass-like sprouts or plant over them in the spring. They'll take probably three growing seasons to reach blooming size.