You need to go to see the espalier gardens that are near you! All sorts of fruit trees growing in all sorts of ways!

River Road Farms
Route 2, Box 245-1
Decatur, TN 37322
Tel. 1 (800) 297-1435 / (423) 334-5349

On a map it looks halfway between Decatur and Dayton, but to the south a bit.

There are soooooo many! Trees include multiple types of apples, pears, figs, walnuts, hickories, pecans, filberts/hazelnuts, chestnuts, pawpaws (I definitely recommend these), persimmon, and plum/cherry/peach trees (although these plum-type species are sometimes problematic as far as pest and disease goes). Then there are grapes, blueberries, rasberries, strawberries, etc. These are just the common types I can think of.

One place you might start looking is somewhere like Stark Bro's (I think they're at www.starkbros.com). There are also many many other mail-order and internet companies that you can check with. I would recommend ordering your fruit trees from a known reputable dealer like Starks. Some of the companies out there that sell fruit trees really really cheap are NOT worth buying from. From what I have seen, if they specialize in fruit trees or vegetables and fruit trees, they are probably gonna be alright. If they sell all kinds of plants, be carefull!

You might also get advise from the UT Extension office. I would not use them as my primary source and I would evaluate what they tell you, but they might be able to give you a lot of information on what specific species, varieties, and cultivars work best and which have problems in this area. I have found them greatly knoledgeable about some things and not very about other things. You can also download and/or view a lot of their publications online. They have papers on multiple aspects of fruit and nut, trees shrubs and vines.