Our downspouts go underground and then come up in the lawn about twenty feet from the house. This works fine, except that the grass keeps growing into the grating at the end. After chopping it out a few times, I've decided to install some sort of grass barrier in a circle around each output, and either fill the center with mulch or pea gravel, or else plant something in there that doesn't mind water but is not invasive (if there is such a thing).

Any suggestions or recommendations would be appreciated!