If you are looking for some blends that showcase the "natural tobacco flavor," check out GL Pease Union Square, Eric Stokkbye 1885 4th Generation and MacBaren's HH Acadian Perique. These are all, in my opinion, great examples of what natural tobacco tastes like.
Natural Tobacco is difficult to define. Are we talking about raw tobacco uncased or not topped? One must be very careful in this arena. There is no tobacco sold to my knowledge that is uncased and in most cases at least lightly topped. If you desire "natural tobacco", there are many blends to choose from. Just look for blends in the non-aromatic category.
I consider 99% of the tobaccos you buy from a reputable company to be "natural."
As it has already been stated, it's very hard to define what is "natural." I wouldn't consider many Drug Store blends to be natural, or anything that is heavily cased. Other than that I think it is open season.
When you say "natural tobaccos have a different flavor," it makes me think that you are comparing aro to non-aro. In that case, yes they do taste very different. Smoke some Lane 1, then some Sam Gawith FVF and you will taste the difference instantly.
When I think of a "natural tobacco" I think of a straight VA or burly blend, or the two combined. They don't necessarily have to be pure, I consider blends like Sugar Barrel, Carter Hall, FVF, OGS, ect... in this category. Perique, Latakia, or heavy aromatic toppings would in my mind remove a blend from this list.
You have to define "Natural".
But in order to do that, you will need to educate yourself on tobacco, from plant to bowl. 99% of all tobacco is grown using inorganic fertilizers and pesticides. Tobacco right off the plant is not smokable. It has to be dried and left/made to undergo a microbial/enzymatic fermentation in order to convert sugars and release ammonia, amongst other important flavor-inducing changes. This can be a spontaneous process, but in commercial tobacco, it is always an induced and carefully controlled activity. Almost all pipe tobacco has some sort of treatment in the processing phase (post-harvest to packaging) that could range from applying a sugar solution or humectant like propylene glycol to an anti-fungal like Mycoban (Calcium Propionate).
After that point, pipe tobacco could be further processed with a variety of flavorings and/or sugars.
So...how "natural" do you want it?
You can buy whole leaf tobacco that has been dried and cured, but not processed into a final product yet. Or you can grow your own tobacco and do the dry/cure process yourself. Many people do this, so it's not impossible, and you wouldn't be reinventing the wheel.
I think you got your answer already. I would add that I have smoked "organic with no chemical additives",according to the manufacturer. I have a taste for "natural" ferments and can tell what has been adulterated with casing. For me casing constricts my throat and is typically in "aromatics". Natural indicates to me no man made chemical flavors or preservatives. I find them vastly superior and widely available.
Some young piper I met the other day outside my barber shop was telling me he only smokes Kentucky Select lit with matches because it's the only Organic Natural pipe tobacco available and it is completely healthy. He also claimed nicotine was actually vitamin B. He was a strange character and was horrified when I lit my pipe with my zippo. I didn't believe him, and have never tried it.
Right on bryanf, that guy is deranged. While I think a pure or purish burley or VA is more "natural" or "where it's at" I don't presume my choice is better than anyone else's. On top of that, my "meadow green" Zippo is my favorite lighter
Niacin was first described by chemist Hugo Weidel in 1873 in his studies of nicotine. The original preparation remains useful: The oxidation of nicotine using nitric acid.
My everyday smoke is called "all natural". Its a bulk blend from my local b&m. Its just flue cured virginia basically, nothin else is in it. Its by far my favorite blend. Very nice, all natural sweet taste.
"All Natural" is defined by me as "anything in pipe tobacco that I enjoy"! I do not tolerate pipe tobacco loaded with Propylene Glycol (a preservative for shelf life). You won't get that from C&D or many other tinned blend manufacturers. drwatson is right. However, by selecting a "tinned" tobacco and inquiring about the ingredients, is still your safest method of selection and check out the reviews at www.tobaccoreviews.com before making a decision if you are uncertain. There are also many excellent tinned aromatic blends. So, if you do not want an aromatic, do investigate before buying as I described.
I suppose natural tobacco minus all the chemical stuff would imply the stuff you attempt to grow in your back garden (yard for the Americans here). I tried this once after reading a book called Grow Your Own Tobacco by Guy N Smith along side a pamphlet from 1946 published by the Tobacco Co-operative in Tilthy in Essex. I found you could get the little buggers to grow but then all your neighbors thought you were growing some other form of recreational smoking product. Once you had taken the flowers off the plants, harvested the leaves, covered them in old sacking to sweat and then hung then in your attic with trays of water around the end result was natural chemical free tobacco. Trust me on this one - it tasted like cr*p, in fact it made a pouch of Clan positively desirable. Friends of mine said it was interesting and that I was very brave (for that read insane) to grow over thirty pounds of the stuff. If you mixed it up with St Bruno it was sort of interesting but it cured me of natural tobacco!