Sorry, I have no idea how rare or common tulip trees may be in your area. I do have one tulip tree I planted in my yard here in Minnesota (unusual for my climate). It's about 23 years old and has been blooming consistently for the last six years.But Tulip trees are said to be self infertile, meaning that if you only have one tree that can't be pollinated by another different tulip tree, viable seeds are very unlikely. I've cut open many, many of my seeds open and have never found any that looked like they might be alive. That said, I do have an encouraging true story for you.
The last few years especially, I've had hundreds of flowers, all producing what look like seeds, but nothing seems viable. This year, however, somehow I had five seedlings grow in the lawn and garden! I have to say, a lot of unusual things happened this year with many old plants that acted differently this year compared to all the previous years. So I am guessing this was a fluke with the tulip tree seedlings, too, but it can happen!
My advice is this winter (probably now) gather a grocery bag full of seeds, if you can. Mix the seeds, say half and half, with potting soil (as mentioned, they do like a peaty mix), and spread in a tray perhaps the depth of a cake pan. Keep moist and outside, by putting the whole tray(s) inside clear plastic garbage bags, and see if anything emerges by mid summer. Keep out of direct sun so it won't cook inside, and don't worry that the mix is too light. As long as the bag is sealed, there will be plenty of moisture. If you see anything emerging, remove the bag and keep moist. If you're late in finding emerging seedlings and they are already a half inch or more high, you will need to just open the bag first, and slowly acclimate the seedlings to exposed conditions over 2-3 weeks.
