Midland. The Midland (please don't confuse with "Midwest") itself is the neutral zone between the North and South. But just because you have a Midland accent doesn't mean you're from there. Since it is considered a neutral, default, "non-regional" accent you could easily be from someplace without its own accent, like Florida, or a big city in the South like Dallas, Houston, or Atlanta.
It got mine right, too. I love filling out that kind of questionnaire. I like the "what do you call it" kinds, too -- you know, the whole lightning bug/firefly; soda/pop/tonic; faucet/tap/spigot stuff.