Once you've picked or purchased your blueberries, spread them out on a cookie sheet to freeze them. This prevents the blueberries from clumping (but if you let them dry after washing, it's probably fine to just freeze them right in the bag). After they have frozen, you can fill up a gallon sized bag and thank yourself all year long!
I went on a quick trip to Baltimore and was able to stop at a delicious farm stand with some Silver Queen sweet corn that we devoured and I've frozen the extras to kick start my corn saving. More on that in August when the corn is sweetest though!
Here's my favorite blueberry muffin recipe:
Adapted from Cook's Illustrated, issue number 98:
2 cups fresh blueberries (or frozen)
1 1/8 cups plus 1 tsp sugar
2 1/2 cups flour
2 1/2 tsp baking powder
1 tsp salt
2 large eggs
4 tbsp butter, melted and cooled
1/4 cup vegetable oil
1 cup buttermilk (I usually substitute yogurt for this)
1 1/2 tsp vanilla
Preheat the oven to 425
Bring 1 cup blueberries and 1 tsp sugar to a simmer in a small saucepan over medium heat. Cook, mashing berries, until berries have broken down into a jam. Allow to cool.
Whisk: flour, baking powder, and salt together in a large bowl. Put remaining fresh or frozen blueberries into the flour mixture and toss until they are coated. Whisk: remaining sugar and eggs together in a medium bowl until thick, whisk in butter and oil until combined, whisk in buttermilk (or yogurt) and vanilla until combined, mix cooled jam in. Using a spatula, fold egg mixture into flour/blueberry mixture until just moistened (batter will be very lumpy with a few spots of flour, do not overmix).
Spoon batter into greased muffin tins about halfway full. Bake until firm 17 to 19 minutes. Cool muffins in muffin tin for about 5 minutes and then finish cooling on wire rack. Makes about 12 muffins.