I've been doing blueberries in my overnight oats, although I usually eat it as a side for my lunch instead of breakfast.

1/3 cup large flake oats
1/3 cup frozen blueberries (wild or regular)
1/3 cup oat milk
+some pumpkin seeds
+some raisens

I also add some frozen strawberry slices, but it isn't nessecary. I usually do 4 mason jars at a time because prepping it every day is a pain, and it stays fine in the fridge that long.