[Spider Girl]

The plants you've described are pretty hardy and not particularly sensitive. If you are just looking for mulch to keep the moisture in and the weeds down, I'd go with a combination of newspaper and grass clippings. Layer the newspaper (no need to shred it) as thick as you like, and then top it off with grass. This way you'll need less grass (and avoid some of the rotting smell which in my mind is fairly innocuous) to hide the newsprint. Just add to the top layer of grass intermittently over the summer, and you should be all set. As a "frugal" New Englander, that would be my approach.