I have two suggestions for decorative items. One is the artificial grass flooring that mimics the look of short grass but acts like a floor tile. It should change the color with seasons just like regular grass, but prevent weeds and debris like regular pavement. The other is a green hedge fence. While looking at all the farm screenshots posted on the web, I noticed that well developed farms become a lot less green. All the available space is covered in stone or wood tiles. These two items could bring back a natural green look to the farms.