Making my "Anglo-Saxon" stew after so long a time has made me think about period foods to serve with it.
Since I usually eat stews with bread, the first thing that I thought of was a plausible Anglo-Saxon or Viking bread. (The cultures were contemporaneous in time, after all, and ate many of the same types of foods.)
A casual search revealed this recipe, from the Viking reenactment group Hurstwic. It uses a mix of wheat, oat, barley, and rye flours, and buttermilk. As is consistent from what we know of Viking cooking technology, it's an unleavened bread, cooked on a flat pan (period pans looked like this one now in the Bergen Museum), but one could make the same type of bread in a broad, greased modern skillet).
Of all the "Viking" bread recipes I've seen, this one strikes me both as one of the more plausible and the simplest to execute. I plan to make some after my next batch of the duck stew. Watch this space to see how my experiment with it comes out.
For the curious, other modern attempts at coming up with a plausible Viking bread recipe can be found at the following URLs:
http://thevikingworld.pbworks.com/Traditional-Viking-Foods (Scroll about a third of the way down the page to see the recipe I'm referring to here. However, this page contains several Viking bread recipes, including the preceding one in this list, in addition to non-bread recipes.)
http://www.ydalir.co.uk/crafts/cook/recipes.htm (This page also contains several bread recipes, as well as non-bread recipes.)
EDIT: The Viking Answer Lady also has a proposed recipe, here. (The recipe in question is located about halfway down the page.) This recipe is an all-barley flour variety that seems as though it would be more like a Viking crepe than a flatbread, but it would probably be tasty, and easier to digest than the Hurstwic recipe. I may try it next.