I'm pretty sure these are blackberries? I want to make sure before I they start to ripen this year because if they are, I'd love to make some jam! Here's some photos of the flowers and the ripened berries from last year. The stalk does have occasional thorns and ridges. I'll probably be posting more photos of plants to identify too, I'm discovering a whole new world in a field behind our house.
Looks like a black raspberry, probably Rubus occidentalis. Blackberries and raspberries are both Rubus. Raspberry fruit are caps that come loose and blackberries cling to the receptacle, when you pick the receptacle comes off with the fruit.
