It is important that foreground, middle ground and background in art work are integrated. I wrote about unity and ways that artists achieve unity, i.e. repetition. You see a second object outside a window or you see the background through the branches of a tree - integration. A cast shadow of one object or the object itself may overlap areas. Reflections of objects in windows or water provide integration. A large shape such as a tree in the foreground might overlap the middle and background of a painting. Artists strive to achieve unity in their works.
I sell my original paintings and fine art greeting cards at my Etsy internet shop. Shipping worldwide is free for all my original paintings. Fine art prints on archival paper or canvas are sold at my Fine Art America shop. I sell images of my art on products, i.e. T- shirts at my Zazzle internet shop. Links to these internet shops are at the top of this site.