Special Ingredients for Better Foods

I thought I would start a topic on secret ingredients that make a dish better but would not be tasted or specific ingredients that add flavor. I like baking and have made yeast bread for many years. It takes a bit of effort and over time I have learned some tricks to better breads.
My favorite yeast bread recipe is for cinnamon rolls but it serves well for basic yeast rolls. The secret ingredient is 1-1/2 cup cooked mashed potatoes. I used a buttery mash potato mix. The potato helps soften the bread and keeps it moist. You wont taste it but the result is good. My family asks for yeast rolls especially at major family dinners. If you have some special ingredient please share with everyone.