Most everything I'm going to mention here can be linked to from here;
http://wiki.radioreference.com/index.php/Milcom_Web_Pages_and_Mailing_Lists
I would start with the Memphis ARTCC - scroll past the ATA100 listings, and use the freqs that follow. Concentrate on the UHF freqs (225-380 mhz or so). I don't know whether Memphis has an airport that uses UHF to coordinate military traffic, but if it does, then that's another target.
If you can hear stuff from those freqs, you can start looking at the DoD FLIPs. Download the AP1B military training, AP1B enroute, VFR and IFR supplements and cull information for the state (if you're antenna is nice and high, and fed with good coax, it should be possible to hear flight activity from areas a fair distance from Memphis, depending on terrain, of course)
Finally, go to the Milcom email website on qth.net. Go to the archives and take a look for loggings from Joe Cobb, who if memory serves, is also in Tenn. That will give you a fair picture of what might be flying around you, even if it isn't in the Memphis area proper.
73s and GL...Mike