As far as I know, all the big raw milk producers (at least here in CA) feed grains for their milk cows.
I ended up finding a place in AZ that looked trustworthy enough, went to the farm and they were all munching on dry hay, probably the best your going to get out there. And I'm sure some grains are used. Its was not organic so GMO feed is a concern, I didn't look that much into it at the time. The farm's site was
http://saveyourdairy.com/ , if that's helpful for anyone else.