When adding additions to bread there are two considerations:
1) Will the additions alter the liquid in the recipe, what I mean by that, is the addition something that is moist, like sweet potatoes or onions. You may have to reduce the liquid in the recipe to accommodate the extra moisture. If it's something that sucks up the moisture, for example oats or bran you may have to add more liquid to the recipe.
2) Will the addition be difficult to eat, (hard or tough) you may need to soften it. This for example would be seeds or nuts. My rule is if it's hard to chew, then cook it before adding it to the bread. Then there may be the issue of additional moisture added to the recipe that you may have to deal with.
Usually I want to keep it simple and not guess at the liquid variable or precook anything at the last minute. So adding dry, or fresh herbs is one way to achieve a different taste without all the hassle.
Add your additions to the recipe on day 2 when mixing the Biga and Soaker together with the final ingredients.
Rosemary Herb Combination per loaf
2 tsp. finely chopped (dried) rosemary or 2 T. fresh
1 tsp. chopped (dried) oregano or 1 T. fresh
1 tsp. chopped (dried) Basil or 1 T. fresh
This is a very nice combination that I use in rolls, but makes good hamburger buns also. When I make hamburgers with grilled onions and cheese these rosemary buns are just the perfect combination.
Olive Bread per loaf
1/2 c. Kalamata olives drained well, pitted and chopped
1 tsp. finely chopped (dried) rosemary or 2 T. fresh
1/2 tsp. sesame seeds
Lots of flavor, but if you don't drain the olives well, you may have to add a couple of extra tablespoons of flour in your final recipe.
Carrot Herb Bread per loaf
Recipe is for dried herbs, if you use fresh use twice the amount
50g carrot grated (about 1 med. carrot)
1/4 tsp. garlic powder
1/2 tsp. sage
1 tsp. dill weed
1 tsp. dill seed
2 tsp. basil
2 tsp thyme
1 tsp cumin seeds
Note: This makes nice rolls and a pretty loaf, and is my favorite for grilled cheese sandwiches.
Sweet Spice Mix (2 tsp of the mix per loaf)
2 tsp. cinnamon
1 tsp. coriander
1/2 tsp. allspice
1/4 tsp. ginger
1/8 tsp. cloves
Use no more than 2 tsp. of the mix for a loaf of bread. The cinnamon will effect the yeast growth. This is great in any sweet bread, quick bread or pancakes. Even 1 tsp. added to your coffee grounds when you perk coffee in the morning and will give it a special flavor. This is perfect in scones, cinnamon toast, or sweet rolls I always make extra because it's so good in any sweet bread recipe
Experiment with your own combinations and create something special.