Have you thought of searching for mills in the Appalachian mountains? They may not show (on the website link below) what you're looking for because many don't like that look, but I'll gander a bet they have what you're looking for.

Here is a link that might be useful: A place to start

Thanks!
Something I just came across that I thought you might find interesting being in Georgia and all....
Gander..... LOL.... I reckon that using a word like that without "Mountain" after it means that you too are a born in Dixielander.....
Anyway, wanting to build somewhat kinda sorta in a way :green", I just wrote these folks and asked adout what they might come across.....

Here is a link that might be useful: Georgia

Try calling Rare Earth hardwoods in Traverse City MI. They can mill flooring to meet your needs. (Just a happy customer, no association)

If you can get it, air-dried walnut is even more amazing. What you are describing sounds like a mix of heart- and sap-wood, which are very contrasty in walnut. Most walnut gets steamed to make the heartwood uniformly dark. Air-dried walnut has an remarkable range of colors within the heartwood as well as the high contrast with the sapwood.

No, not born. I'm a halfback.. I'll let you figure that one out. I've watched a lot of Andy Griffith and say things like "fine and dandy" or "fine, just fine"...it fits up in the mountains. Yea, Rare Earth has some gorgeous stuff too. I've heard of Eutree but no experience.

Depending on your budget you could look into Carlisle. They specialize in wide plank and have a good selection of Walnut.
Most Walnut is steamed as someone above pointed out. Steaming makes the dark heartwood color spread into the sapwood increasing the yield.
You'll want rustic grade unsteamed Walnut.
I can't speak to the accuracy of the person above recommending air dried wood. Generally air dried wood does not reach a level where it's dimensionally stable so in my opinion you should insist on kiln dried wood. All kiln dried wood is air dried until it reaches a certain level then it's kiln dried.
Another source for Walnut would be Homerwood which is now owned by Armstrong. They offer Walnut in the widths you want but I'm pretty sure it's all steamed.

Thank to all y'all for you replies!
I believe that y'all are right about the steamed thing and color bleed/variation.
I knew there was something "odd" we were told about the floor we saw and I think that it was that being an old locally milled walnut it was from locally cut and sawn walnut that had been stickered and air dried and then milled.
IMNSHO, air dried lumber is just fine when it comes to dimensional stability as long as it sits long enough. Here in west NC humidity can be anywhere from very low to damn near 100%, depending on the season, the day the time the wind the whatever. Quite some. like maybe 20 years ago when the kids were little, me and a friend built he and his wife and kids a small house and floored it with 2X8 T&G pine that was locally cut and air dried and then milled and stickered in a barn for maybe 6 - 8 months. We face nailed the floor with cut nails and did a sand and some kind of clear coat "hardening" oil stuff that Steve's wife found somewhere. They are still living in the same house (though a good bit bigger now) and the pine floors are still, and IMO even more beautiful than when it was new.

Half back eh? You made it down to Florida and didn't wanna go all the way back? I am originally somewhat of a rarity, a 60 year old native from far far south of the Lake (near what is now a days known as Kendall). A native Floridian whose parents are from there too and whose family was there before, as my grandma used to tell us "before Mr. Flagler brought his railroad". I left in 1973 when it seemed that since half the people eating up what was once our personal tropical farmland paradise in far south Florida were there from North Carolina, the best move would be to where space was opening up from everybody in NC leaving..... Turns out it was a really good plan.

And now, regarding Andy and Opie and Barney and Aunt Bee, the nearest crossroads to our "old place" that is now for sale, is Mayberry Road. Not too many miles and a whole lotta turns from Mt. Airy, NC.

I have soo many samples of Walnut from various companies I have found on the internet...here are a few you may want to look at...keep in mind, I wanted plain walnut, not black walnut, but they were all helpful and they all sent me samples. We decided against the walnut because is is so soft. I would love a reclaimed walnut floor, but I cannot afford it...

Reclaimed Designworks (David)
Olde Wood Ltd (Matt)
Elmwood Reclaimed Timber
Carlisle Wide Plank Flooring (love their stuff..but a budget buster!)

That company called Eutree that someone mentioned above was great returning my calls, but I never heard back from them...they are new to the industry...I think just really busy

Today turned out to be one of my lucky days!
I called a fellow about some 5 and 6 inch black locust I was told he has a bunch of. A friend has a planer and says that if I buy a set of blades he'll mill it for me for.
So me and locust man are talking away and I asked where he got the locust from. He starts telling me about his horses and shows me pictures of these two enormous horses all decked out in harnesses and reins pulling great big logs behind them.
He tells me about his being into what is called "sustainable forestry" and how he refuses to turn a tract of land into what appears to be a lunar landscape after a thermo-nuclear war and minimizes the use of machinery to loading logs as close to the road as possible.
Next thing I know he is asking me what else I might be wanting besides Black Locust, so I told him about the kind of Black Walnut I am looking for. Lo and behold he says he has around 200 boards of eight inch wide one inch thick Black Walnut that is just what I am looking for. He says it seems that no one wants unless they get to sort and pick it and price it for "color". And, he says it is all in 8, 10, and 12 foot lengths that he says has been sitting in a barn since the summer before last. I am going to take a good look at his walnut and locust one day late next week, and if it looks even half way like what I am looking for, I am gonna buy it on the spot.
Then again, he asked if we have any decent timber on either of our our properties, and as soon as he heard "yes", we start talking trading some of our trees for some of his Black Walnut and Black Locust lumber and mill work.. And maybe we would be willing to trade out some pasture time for his horses when he is working "in the neighborhood"? So maybe, just maybe, we'll get all of our flooring for "free"
I just love living life in little bitty towns and way out in the country, though a week in the big city every once in a while is a nice distraction. We're going to my personal favorite big city, Chicago, for ten days in June! To each his/her/their own I reckon.....
If he has something like close to 200 sq ft of something else really unique and interesting, Cyndi can just kiss her heart pine bedroom floor dream goodbye..... We have some huge Beech and Hickories, and quite a few rather large White and Red and Chestnut Oaks too, but I am looking for "character". I know where there is a very large Osage orange that the folks who own it tell me they are tired of dealing with the millions of oranges that it drops year after year, and just might let me have for cleaning up whatever mess taking it down makes. Osage orange is a very rare tree in these parts.... a local exotic so to speak. I know where there are a few groves of Honey locust trees near by too, which is IMNSHO, as beautiful and hard as a rock wood as you'll ever find anywhere east of the Mississippi.
Thanx to all y'all for taking the time to comment/reply. If all works out, I reckon I'll be posting pictures of what my wife is going to threaten to kill me for real for buying without any input from her.

What luck! I am so jealous about THAT deal. Enjoy your new floors.