Sheep seem to be a good answer.
They do the cutting, are quiet and cute and they produce excellent fertilizer as a byproduct. Apparently it is difficult to train them to graze in perfect rows and to a predetermined height. Otherwise, it's a great idea. You can try to convince your spouse or your children that it is either fun or a less expensive way to workout than the local health club. If either of these works for you then please let us know how you do it.