This stuffing's bold herbal flavor comes from generous amounts of fresh sage, thyme and parsley, as well as poultry seasoning: a ready-made mix of dried herbs, including marjoram, rosemary and oregano. We especially liked Bell's Seasoning. Using two types of mushrooms—portobellos and shiitakes—built on the herbs' woodsy, earthy flavors. If your supermarket only sells whole portobello mushrooms (that is, with stems), you will need about 1½ pounds to account for the weight of the stems. If you'd like to do some of the prep in advance, prepare the recipe through the toasting and seasoning of the bread cubes, then reserve them and the remaining roasted mushrooms separately; refrigerate in airtight containers for up to two days. About two hours before serving, remove the mushrooms and bread mixture from the refrigerator and proceed with the recipe.