Answer: I hope you meant to say that you cut the flower stalks down when the flowers are spent, not that you cut the leaves off! The rhizomes need the leaves to produce and transport energy so they can grow big and strong. You should allow the foliage to remain on the plants until it dies down naturally. With that said, yes, you can allow the seed pods to mature and then collect and plant the seeds. The resulting plants may not look at all like the parent, but you may have a special hybrid iris.
The seed pods will grow larger through the summer, eventually turning yellow or brown and cracking open at the top. If the exposed seeds are brown and glossy, they are ready for harvest. The seeds will need a chilling period and a period of moisture so plant them outdoors as soon as you harvest them. This way they will experience the cold of winter and the moist soils that spring rains bring. I'd sprinkle the seeds over the top of the soil and cover them with a light cover of fine soil or about a half inch of fine compost or peat moss. This covering will keep them from washing away in rainstorms.
Best wishes with your irises!
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