I have been looking everywhere online to find out about my beautiful double headed tiger lilies. The question that I have, is what are the black seed looking growths that are forming on the leaves of my Tigerlily? Are these seeds that you can use to grow? What are the purpose of these pods that are growing? I would really appreciate some help on this. I have been researching all over the Internet and I can't find anybody with any information about this. Please help me!

Those are called bulbils. They are essentially small bulbs that will drop to the ground and bury themselves and grow into new stems.

You can also carefully pick them off at the end of the season, when the stem starts to die back, and plant them yourself. As Dave said, they'll produce new plants identical to the parent.

If it helps, it sounds like you have Lilium lancifolium 'Flore Pleno':