I still say it's in the Birch family, I used a magnifying glass to look close at the unique Bark in the picture Travis posted. It's exact to a Birch tree near by where I live and the leaves are serrated exactly the same way. But the only other possibility it's a flowering Plum tree. However the bark peels differently on the Birch tree then the Plum tree, and looks like the pictures Travis posted. Whether it's Birch, Black Cherry or flowering Plum, all woods listed can be used to make a pipe. However the Plum wood would have a very different grain and many more knots in the wood.
KEEP ON PUFFING!!!