Combine warm water, honey, yeast, and butter in a bowl. Let stand for 5 minutes, until foamy.
Combine flours, oats, wheat germ, salt, and flaxseed, and caraway seeds if desired, in a large bowl. Add yeast mixture and buttermilk, and mix with your hands until flours are almost fully incorporated. Turn out mixture onto a clean surface, and knead until smooth, about 3 minutes.
Lightly coat a large mixing bowl with cooking spray, and place dough in bowl. Cover with plastic, and let rise in a warm, draft-free spot until doubled in size, about 1 hour.
Turn out dough onto a lightly floured surface, knead for about 1 1/2 minutes, and roll to 1/2-inch thickness. Using a 3-inch round cutter, cut out rounds. Roll and cut scraps once. Line a rimmed baking sheet with parchment, and dust with cornmeal. Place rounds on sheet, cover with plastic, and let rise in a warm, draft-free spot until puffy, about 20 minutes.
Heat a large griddle or 12-inch skillet over low heat. Working in batches, place rounds 1 1/2 inches apart. Cook until golden brown and dry, about 7 minutes per side. Let cool for 30 minutes; split with a fork. Toast, and serve with butter and preserves if desired.
Muffins can be stored, wrapped in plastic, for 2 days, or refrigerated (up to 1 week).