Mike, we know where you can get some!
Jamie, the natural habit of sourwood is to send up straight shoots in its new growth, weather from the base of the tree or at the terminal buds at the top of the tree. Also, being an under story plant that grows straight, when it becomes unsupported by the surrounding canopy, sourwood has the tendency to lean over and subsequently shoots will sprout along the top side of the trunk.
Where I get most of my shoots is along the road side where the DOT mows the road banks every 3 or so years. Sourwood seems to be a heavy seeder and many seedlings develop along these sunny road banks. After a few years of growth the mowers come back through, cut them back to near the ground and new shoots sprout and head for the sun. After their 2nd year of growth is my favorite time to cut them.
I have also noticed a variation amongst individual sourwoods as to shoot lengths. Some grow is only a foot or so and some will grow up to about 6' and in my observations this remains consistent from one year to the next.
If you were to go back to those landscapes where you planted sourwood and cut them to the ground, you would see plenty of shoot growth.
I haven't seen Fred lately either. I'm with a different company so I don't frequent the coffee shop were we used to see each other. Pat