Garden Pests and Diseases: Green bumps on Black Eyed Susan leaves - Aliens?, 2 by CapeCoddess

CapeCoddess wrote:
These leaves are from the lower sections of 3 different plants in 3 different regions of the same garden. Originally I thought that a passing flock of birds got em, but that's not it as it's IN the leaves and doesn't wipe off. The splotches are purple and look like ink stains, the bumps are green and raised on the front of each leaf but concave in the back.

Have you folks ever seen anything like this? If so, what is it and what do I do about it?