I see you!
Livestock First Ranch
Bar M Ranch
Burgundy Pastured Beef
In addition, if you need a special cut quickly, the Local Yocal just off the square in McKinney runs a full service retail butcher shop carrying locally raised beef from Matt Hamilton's Genesis Beef. They also carry local chicken, pork, lamb, goat, eggs, dairy and honey. Good stuff.
If I'm picking up at a farmers market, I like to call ahead and preorder. Farmers like to know they have orders before they get to market, and this helps them make sure they have enough product. Additionally, some have limited eggs and give priority to orders that include meat, so it's a good idea to get on their list before market day.
Don't be afraid to ask questions. Every one of these farmers is proud of what they produce, and happy to talk about it with you. Know your farmer!