I'd think about ginger. I'd also consider thyme or sage for something a bit unusual. You could cook a bit blackberries and sugar in a saucepan, then mix them with different spices or herbs and see what you fancy.

i'm thinking Chinese 5 spice might be an interesting flavor for the blackberries. I have enjoyed it with dark fruit.

To add to hardlikearmour, basil is wonderful with blackberries. Also consider grains of paradise which give a rich flavor to berries.

Oh, I forgot - if you use dried basil use a few ground fennel seeds with it. And if you use fresh, just sprinkle chopped leaves on top. And please, please let us know what you come up with.

These are fantastic ideas, thank you so much! I will definitely have to play "chemist" on the stove.

I will definitely let you know what I end up using, my boyfriend will be weighing in on the decision also; we might like two entirely different flavors, who knows! (altho these all sound delicious).

My favorite spice for blueberry muffins is 1/4 tsp (a very small amount) of star anise. Picky people don't like it, though.

So, I made the cobbler last night and it turned out awwmazing!
I ended up using the basil flavoring, and tore tiny pieces of fresh basil leaves and placed them throughout the blackberries. I also used zested the lemon and put that into the flour mixture which provided an incredibly flavorful crumble topping.
Thank you for all your suggestions! I tested out the Chinese 5 spice and I'm going to save that for more of a winter blackberry cobbler, (or whenever I'm feeling in a more homey mood), but the basil was refreshing, light, and added a lot of flavor depth to the dish. I'll actually add more leaves next time.
I wasn't able to test out the ginger unfortunately, because I also think that would have a nice light, spring flavor...but I do have two cartons of blackberries leftover, so I believe I can think of something!
Thanks again

Picture!

I like the taste of cinammon with blueberries, though the other proposed spices sound quite interesting.