Here is the place we are getting the seed from.
http://www.grasslandwest.com/ They came up with a special mix for us, which isn't listed on their site, but I did notice that they have a "Yellowstar Fighter" mix that we may try. Just not sure if it will do okay where we would put it, since it isn't in an area that we can irrigate. I think if we had pink and purple thistle, I could convince my DH that it isn't really as evil as the yellow variety!
But, that may take a few years! The previous owners of this place let it go, and never tried to stop any of the horrible weeds, so we are infested with it. We would really like to just burn the fields, but haven't gotten up the nerve to attempt anything like that yet. To us, it would be better than a chemical attack, but we'll probably have to resort to that in some areas. Some of our neighbors burn their wheat fields after they have been cut, so we may get one of them to help us with that. It's just scary thinking about it, but it is a very common practice here, and it does control the star thistle. However, we're new to farming, so we have a lot to learn!