In the meantime, I've bought a couple small loaves of Storye at Whole Foods, because it looked about like something I remembered from when I was my son's age, and a decent deli finally arrived near where I grew up and my dad was excited to introduce us to things like Edam and Gouda and Cervelat (boy, the cervelat thing stuck -- whenever I got to the Netherlands, I eat a lot of that).
The Storye bread makes some claims about having no yeast/no added yeast/being yeast free. This is present on the product and on the website. I'm a little skeptical of claims like this, because I believed (it turns out erroneously) that if you make some kind of grain and water or potato and whatever starter, ferment it and then use it to make a bread rise, you've just corralled a bunch of wild yeast.
It is, actually, not that simple.
Here is an NPR piece about Appalachia "salt rising" bread (no salt involved in the rise, duh); the rising agent is stuff like Clostridium perfringens.
I don't know what Storye is corralling. The bread is tasty, close to but not identical to what I remember. I'm a little worried about the claim of 9 g of fiber per slice, given that I foolishly just had a two slice sandwich (maybe I should have just had one and cut it in half).