I'm looking for a quick growing ground cover for our pen approx 30'x20'. My ladies were moved into a new pen this spring before the existing grass even had a chance to turn green. Now the pen is a wasteland of dirt and straw that I have added. I am planning on fencing in our back yard so they can range while the new cover grows. I'm just not sure what will best for them to forage in that can grow quickly. Any suggestions?