What Brands make butter from grass fed cows?

A favorite, fairly easy-to-find brand is Kerrygold, an Irish dairy whose cows are all pastured and whose butter is incredible. I get mine for $2.69 at Trader Joe's, but I've seen it in basic and specialty grocery stores, too (albeit for slightly higher prices). Look for the silver foil (unsalted) and gold foil (salted) packages.

Anchor butter is another tasty one. It hails from New Zealand, land of reliably grass-fed lamb, and I've seen it at Whole Foods for a reasonable price. If you can't find it there, you could always order online in bulk. Just freeze the extras.

Organic Valley has a seasonal pastured, cultured, salted butter that usually appears in spring, which is when the grass is at its greenest. I've had it a few times. It's good and a bit tangy, and it comes in a green foil package. Skip the regular Organic Valley stuff, which gets some grain.

Check farmers' markets. If you've got a dairy stall, you've probably got access to good butter. Talk to the producers about the cows' diet.

Update: It's not 100% grass fed. It is almost 90% grass fed, and supplemented with feed that includes soy and corn per their own website.