Combine the blueberries, lemon juice, and flour in a small bowl and mix until the blueberries are coated. Place into bottom of pan (see note).
Mix the flour, oats, and brown sugar for the crisp in a seperate bowl. Cut the butter into small cubes and add it to the bowl. Smash the butter into the dry ingredients with a fork. You want the mixture to be somewhat crumbly, not totally combined. Pour mixture over blueberries.
Bake for 15-18 minutes or until crisp and bubbly. Enjoy ;)
Notes
I have a small ceramic dish that I used for this. I found it at a thrift store, otherwise I'd give you a link. Any small single serve dish that can go in the oven will work for this. If you don't have anything like this, you could divide the mixture between two muffin tin cups.
This recipe is heavy on the crisp topping, but if you like yours with more fruit, you can double the berry portion and half the crisp portion.