For the last four years I've spent a lot of time cutting down thorn trees on my family's farm. I know this seems wasteful of a practically good tree, but there are a lot of negatives of having thorn trees around. Especially if you like your tires or even your feet. The poison released from a thorn is much more painful than it poking through your skin.
I purchased some tree seeds from http://www.seedrack.com, and the other day they finally came out of my fridge and I was able to stick the seeds into some soil. I really hope some of these grow.