Blueberries because my kids love them.
Earlier this week, I noticed that I still had some frozen pumpkin to use and decided I’d make pumpkin muffins (with chocolate chips — for the extra antioxidants, of course) today or tomorrow. While I was assembling them this morning, it suddenly occurred to me that I had frozen blueberries, too, so I added a cup of those (dusted with flour to ensure even mixing in the batter). The batter got tinted a rather odd green hue, but when they baked up, the muffins were a normal orange.
And the kids love them, which makes me happy.