There's a couple tracks down just south of Hattiesburg (The Landing and Rock Hill). The Landing is pretty nice, really sandy though. You can get directions to them from your local bike shop, I can get there, but can't remember any landmarks good enough for directions. One track practices on Tues. one practices on Thurs., I can't remember which is which.
We have a small practice track just south of Meridian. If you get on Hwy45 South out of Meridian, you'll come to the Garrisonville Rd Exit. Head away from Meridian. About 7 or 8 miles down this road, you'll come to a left hand turn with a guard rail on the outside of the turn. Halfway through this turn there is a road that branches to the right called Aycock Rd. Turn here. About 3 miles down on the left will be the track, you can't miss it. There's an honor box, so please pay as you enter. Open 7 days a week, $10 per rider. I'll be there today as a matter of fact. Usually there a couple times a week. The biggest turnout (6 or 7 riders) is on Sunday, around 1 pm.
The track up toward Louisville: You want to get to Preston, MS (there's a 4 way intersection in the middle of town)....I take 495 North to Preston, there'll be a quicker way for you. You want to take Hwy 397 North out of Preston, about 6.5 miles to Nanih Waiya School. You'll take the third right (Han Williamson Rd.)past this school (the second right you come to will be a store at Hwy 490....you want to take the next right past this store). The track is a couple miles up this road on the left. It's built into an old speedway track. I don't know anything about practice times or race days there wasn't any info posted and I don't know where to get it. It's a decent track though, Supercross layout with a couple of pretty big jumps.
If you get any info on any of these tracks (practice times/race dates), please post them!