Tim~
Yes, Yellow Poplar=Tulip Polar=Tulip Tree - it's in the Magnolia family. It's a great, straight-grained wood. I use it for painted trim and cabinet framing, etc, for interior use. It is not at all rot-resistant - which I learned the hard way. I used it for the roof rack on my Element - once a seam opened up, even though it was sealed with epoxy, rot began its magical work. I had to cut it out and repair it with a dutchman.
Come to think of it, I've got a big Black Willow down right now - the limbs are 18" through - I should bring a few pieces out of the weather and see if I could make a decoy or 2 out of it once it cures.
All the best,
SJS