In 2008, I decided to reduce the amount of turf grass in my front yard. The original plan was to create a small island bed in the middle of the yard. I was not happy with the shape of the bed, so I gradually removed more and more grass until most of the front yard was gone.
I would have removed all the grass, but I read that front yard native landscapes are better accepted (or tolerated) if they have a border around them. To accommodate neighborhood sensibilities, I put edging around my native planting and left a small strip of St. Augustine grass on each side. I think the strip of manicured grass emphasises the point that the natural flowerbed is intentional and maintained.
I decided use straight lines for the front and side borders of the of the bed. I just could not get the curves in the slope of the soil in the bed and curves of the pathway between the original bed and the new bed to complement the curves of the borders.