I've stopped and looked at this post several times. I have an incurable weakness for blackberry jam and blackberries in general. They grew wild where I grew up...
The only thing that can even remotely compare in my world is Huckleberries. I got some of that this summer when I was up north. I mean, is there a human that can resist a huckleberry milkshake? Not this one.
And I also had a blackberry shake just to keep the equation balanced.
Never heard of a huckleberry milkshake or huckleberries. Sounds interesting though!