Now wouldn't this be cool to have in the yard? No not the gnomes, the green roof! I took this picture last year at the Bloom'N Garden Expo in Williamson County last year. It's a great example of nature and man working together to make something good for both. Green roofs are catching on all over because they help to ease water runoff. I'm not ready to build my shed yet but when I do this is something that I am considering. The green roof consists of several layers designed to prevent water from leaking into the structure and to provide growing material for the plants. Green roofing systems tend to be a little more expensive than conventional roofing systems but the cost equalizes over time. This particular green roof would make a perfect little house for the family pet or could easily be constructed on playhouse for the kids (hmm ... there's an idea!). The plants on top consist of sedums, Hen's and chicks (Sempervivums), phlox and a few other miscellaneous plantings. Generally drought tolerant plants that have shallow root systems work best.
This might be the closest I can get to my own hobbit hole!
For more information on green roofs check out Growild.