Take off any stems, wash them, spread them out on a cookie sheet and freeze them. After they're frozen, put them in quart freezer baggies and you'll have fresh berries all year long. I pay $3 and up for these in the grocery store.
Blackberry cobbler, black berry pancakes, jelly (remove the seeds), jam, cheesecake topping, pies, etc. Anything you can do with strawberries you can do with blackberries.