I have this tree growing in my backyard (located 30 miles south of Birmingham), and I'm curious as to what it is; it's quite a nice-looking tree, and I'd like to replant some of its seeds.

http://i34.photobucket.com/albums/d115/UltraSonic007/tree_0_zps8f7157f8.png (a shot of the whole tree; the ground is a few feet out of frame; the lowest hanging fruit cluster is within reach, so I estimate that the tree is over 20 meters tall)

http://i34.photobucket.com/albums/d115/UltraSonic007/tree_4_zps3193cabf.png (a close up of one of the fruit clusters)

http://i34.photobucket.com/albums/d115/UltraSonic007/tree_5_zps7a8a42ab.png (another close-up including some leaves and fully ripened fruit)

http://i34.photobucket.com/albums/d115/UltraSonic007/tree_3_zpsce707610.png (one of the fruit; its coating is quite sticky)

http://i34.photobucket.com/albums/d115/UltraSonic007/tree_2_zps2c98c602.png (a fully ripened fruit, now with the texture of a nut)

http://i34.photobucket.com/albums/d115/UltraSonic007/tree_1_zpsd37be1ca.png (the same ripened nut, split open: the seeds have long since dispersed)

It's been growing quite rapidly over the last decade; in that timeframe, this tree went from about five feet to that! Furthermore, when the leaves wilt in the fall, they turn brown, and it's located in a wooded area.

Any expertise would be appreciated!