Salt and light. Salt of the earth. Salt is a big deal. From the wikipedia article, History of salt:
Salt's ability to preserve food was a foundation of civilization. It eliminated the dependence on the seasonal availability of food and it allowed travel over long distances. It was also a desirable food seasoning. However, salt was difficult to obtain, and so it was a highly valued trade item. Until the 1900s, salt was one of the prime movers of national economies and wars. Today salt is almost universally accessible, relatively cheap and often iodized.
Although sodium and chloride are both required for survival in humans, you they don't have to be consumed in the form of salt. We figured that because most people, in North America, and around the world, have had salt, from the sea, from salt mines, or from salt licks, we should be able to have it too, especially because of it's importance in preserving foods (like pickling cucumbers or fermenting sauerkraut in brine). We did learn that Michigan is one of the leading salt producers in the U.S., thanks to the Michigan Basin, which has been under inland seas multiple times in the past.
Without yeast, we couldn't make bread and we couldn't make wine. We allowed buying packets of wine and bread yeast from the store. Of course, we could have tracked down a sourdough starter (still looking) or collect "used" yeast from a homebrewer in town, but, we didn't. So technically, we could have gotten yeast locally. The packets ensured us that our precious bread and wine didn't end up not working.
Baking soda and baking powder
Baking soda, or sodium bicarbonate, is another salt, chemically. Baking powder is baking soda with an acid salt added, usually calcium aluminum phosphate. Sodium bicardonate occurs naturally, but it is most often made chemically. Sodium chloride (table salt) was heated with sulfuric acid, producing sodium sulfate and hydrochloric acid. The sodium sulfate was then heated with coal and limestone to form sodium carbonate, or soda ash, from which baking soda is extracted. Here's something interesting about the history of baking sodas:
The development of baking powders began with the discovery of carbonate materials. One of the first carbonates was potash (potassium carbonate, K2CO3), a material that was extracted from wood ashes. During the eighteenth century, potash production had become a major commercial industry. American colonies exported huge amounts to England where it was used by glass factories and soap manufacturers.
Potash's usefulness to the baking industry was discovered during the 1760s. Prior to this time bakers had to hand knead dough for long periods to get the proper amount of air mixed throughout. For recipes which called for sourdough, pearlash (concentrated potash) was added to offset the sour taste. By chance, bakers found that these types of dough rose quickly. Evidently, the pearlash reacted with the natural acids in the sour-dough to produce carbon dioxide gas.
Because baking soda is made via a chemical process, because it is sometimes needed as a leavening agest, and because it is used in such low quantities, we allowed ourselves use of baking soda and baking powder.
Well I think that's it, really. No other exceptions. Well, there were some technicalities. We found local butter--goat butter, from the Amish in Arthur, IL. We bought a quart, but used it all up. It's not convenient for us to go back to Arthur to get more, so we are now using cow butter, from Wisconsin. That goat butter made some awesome popcorn though...
The other technicality is for cornmeal. Moore Family Farm mills corn into different coarsenesses...fine cornmeal, coarse cornmeal, and polenta. But, sadly, the corn is from Ohio. The wheat they mill is from Montana. But luckily, there is Peterson Wholewheat flour, of which we just bought 25 lbs! But we haven't found locally milled, locally grown cornmeal, so we've allowed ourselves the Moore cornmeal. At least it's milled locally!