Google "create moss lawn" and see what you find. My daughter's mother-in-law created a moss garden (not a whole yard) some years ago at a previous house. Seems to me she ordered moss from somewhere. Maybe used buttermilk. You need to have conditions suitable for moss (sounds like you do). You would probably want to have stepping stones to walk on through the yard and a hard surface for any lawn furniture since it's easy to tear moss up. Weeds could be a problem. I don't know how herbicide affects moss.