Rinse blackberries well without mushing them. Becareful of stickers, bugs, foxtails, etc.. Allow to drain and then place in a large bowl.
Add to berries the flour, lemon juice, vanilla and then mix.
Add in the sugar and continue to gently mix.
Line a 9 inch pie plate with the lower layer of pie crust (whether store bought or homemade...my recipe is a secret ;)) ...Do not poke too many holes into this crust because it will want to stick to the plate. So go easy.
Pour in the berry mixture and then place the 6 tbsp of butter (6 individual tbsp's) scattered on top of the mixture and push down a little bit so that the juices cover them, slightly.
Finally add the top layer, pinch off as normal, make a couple of slits in the top to prevent bubbles/spill-overs and then back at 350 degrees for about 35 mins or untl crust is golden brown.
Allow to cool completely or if you can't wait that long, serve somewhat warm with a big scoop of vanilla ice cream.