Have you considered just 'burying' the flat stones so that they are just above the level of the dirt? Then you could let the grass grow up between and around them, and when comes time to mow, just roll right over stones to cut the grass.
SSQ has thought about doing this in lieu of an asphalt driveway for the new place. Actually it would be just two 'strips' of paveing stones to roll on, with the grass growing up between them.
yup... we were just wonderin' about havin moss between the stones... I don't want this to turn into another obstacle to mow and weed whack around... I want low maintenance... course, diggin' down any level 'round here is a major undertaking...