Who sells unstabilized (truly raw) oats in the U.S.?
Oats from Tractor supply are definitely uncooked (about $15 for 50 Lb). I've planted them to grow cat grass for years. Unfortunately, they are also not hulled. Hulling is usually done by hurling the oats at a steel wall at about 70mph, then separating oat from empty hull and oats still with hull by fractionating through a stream of air. Naturally, buoyancy depends on a groat's size, as well as its density. It's a tricky task to run at home. You can make a centrifuge out of an old angle grinder, with an impeller designed to get the oats up to speed, but the air driven density separation is quite hard to mimic with only an 8 foot ceiling. There are other ways the separation can be accomplished, but dry oats tend to build up quite a static charge when you roll them around.
For whole, uncooked, dehulled oat groats you'll want either a food coop or a health food store. At about $1.50 a pound you can usually do as well or better than the 50Lb sacks available through Amazon.