Jill at La Vida Locavore has an interesting link for a site that lets you decode the plant code stamped on dairy products. I checked my Kroger milk and it came from plant 20-283 which happens to be in Hutchinson, Kansas and my sour cream and cottage cheese(also Kroger) came from a dairy(27-143) in Tennessee. Cool. I couldn't find a code on my Trader Joe's yogurt but it may have been on the aluminum seal which is gone.
Want to know where your milk is from? Check out WhereIsMyMilkFrom.com