Stumpy makes a good point about rumors.
The Oklahoma story started in summer 2007. The press was invited to an event with Oklahoma's governor and Disney executives. Immediately, rumors began that Disney would announce a theme park for Oklahoma. It turned out to be nothing more that an event to officially announce that Oklahoma would be at the Epcot Food & Wine Festival later that year. But, by that time, the Disney Oklahoma theme park rumor already had a life of its own.
The Mississippi rumor dealt with a site in northern Mississippi, somewhere south of Memphis, Tennessee. While it's doubtful that any conscientious journalist would have reported that Disney actually purchased land for a new theme park, I wouldn't be surprised if journalists reported the rumor as a rumor. I don't know what the real story was, but clearly Disney didn't really buy the theme park site in Mississippi. Possibly somebody started the rumor in hopes of somehow making money off real estate in northern Mississippi.