I've grown various varieties of achillea - white, cherry, gold - over the years. Dad has a cherry still in his yard and that has seeded into his lawn grass.

He's quite happy with it. Dad has never used a weed'n'feed but takes fairly good care of his lawn (especially considering that he's 88 :o). He mows very, very close but still - this plant, that would reach 2 feet or more if permitted, has formed a few nice mats is some of the drier areas of his yard. It is surpringly comfortable to walk on, also. There is no "stubble" or really much coarseness.

I don't think that it would be an answer to my shaded lawn problems (overseeded and here's hoping that it grows) but it looks like a sensible choice in the sun. I doubt if it requires the quantity or frequency of watering that KBG does.

The link below is a photo of a SoCal lawn but I can attest to achillea's success in NoId.

Steve

Here is a link that might be useful: Yarrow Lawn in Los Angeles