This is a recipe that we used when I was a little girl that my dad had in a little paperback cookbook. I have tried other ones and this is still my favorite. My daughter's favorite part of making them is putting the liners in the pans:
1/2c butter, softened
2 tsp baking powder
Preheat the oven to 375degrees. Cream together the butter and sugar until fluffy. Add the eggs one at a time mixing well. Add the vanilla. In a separate bowl, combine the dry ingredients and add them alternately with the milk to the batter. Fold in berries lightly. Spoon into greased or lined muffin tins. Bake at 375degrees for 20-25 mins.
Note: I made some of them with a mini muffin pan and it was a huge hit. I bake those for around 13mins.