Might want to try finding some stuff orginating from New Zealand. I have read that 'all' of their cows are grassfed. I don't now if that is strictly true, but seems like a good potential place to start for naturally raised beef products. As for anyone else, if they are not bragging about how their animals are grassfed and charging more because of it, you can assume their critters are not grass fed. Most cows are not grass fed and that includes milk cows. Adding a bunch of crap to their diet increases milk production-decreases quality but increases volume. Most of the few producers of grass fed have figured out they can fetch higher prices if their stuff is not grain fed and so advertise and price accordingly. Whereas cheese producers are looking for lower priced milk. They are not going to pay extra for grassfed unless they plan to advertise and try to get higher prices for it being grassfed. Unfortunately, right now, not many people other than those involved in paleo care if the animal is grassfed or not so the market demand is not high enough to support many suppliers. Basically, if it does not say grassfed, you can pretty much assume it is not.
I looked all over my local health food markets but could not find anything grassfed. Right now, the main market is looking for the word 'organic.' PLus there are those few who say 'free range' for the chickens, which only means that after they lived in cages for most of their lives and are scared of the outdoors, then a small door is put in so that they could go out if they wanted, but they never do because their brains have been so warped that they won't go out anymore. They are too scared. That is why I do not pay extra for stuff marked 'free range.' It's a scam I will only pay for the word 'grassfed.' Even then, you have to be careful because many cows are grass fed at first but then later sent to the corn feedlot to fatten them up before slaughter. And by the time they get to your dinner plate, the omega profile and other benefits of grass fed have long since been 'corned' out of them.