Pickle some. They make a fabulous garnish with most types of game. I make a pickling liquor with red wine vinegar, water, caster sugar, star anise, cinnamon stick, pink peppercorns and bay leaf. Heat all of these elements until the sugar dissolves and then allow to cool. Put your blackberries (brambles in this part of the world) into a sterile/sealable jar and then add the pickling liquor and they will keep in the fridge for ages. Add a few to the plate with a drizzle of the liquor - they go brilliantly with grouse, pheasant, partridge and venison, in fact with pretty much any game.