I'm from South Dakota and while I haven't yet hunted turkey in either the Black Hills or the Gregory area, I know both of them have a reputation across the country as being prime areas. There's just a ton of turkeys there, just like there's countless pheasants in the areas in between.

Also, the NWTF and the GFP frown deeply on 'stocking' areas with 'raised' turkeys. In fact, when they hear of people wanting to do that, they try to work a trade with other regions of the country to bring in adult wild turkeys, rather than let someone release farm-raised birds. Because of that, there are very few, if any, turkeys that aren't truly wild around SD. Many of them may not be as wary as those out East, but that doesn't mean they're farm birds.