Howard Southdowns lamb can be found at the following farmers markets - 

Stillwater Farmer's Market
    Wednesday & Saturdays 8am-1pm

Edmond Farmer's Market
    Saturdays 8am-1pm

Guthrie Farmer's Market 
    Friday 6-8:30pm

All lamb is processed and packaged in a Oklahoma inspected and USDA certified facility;
Homestead Meats & Processing Guthrie, OK 

The American Lamb Board is an excellent resources for all questions lamb!
Click HERE to be redirected to their lamb cooking school where they will go over cuts of lamb and different cooking techniques! 
If you are just looking for recipes then click HERE!
For a handy chart on cooking times and temps click HERE!