Five yeas back while touring around Scandinavia, I saw several houses with grass roofs in Norway.

Norwegians have their own way of going green, and quite literally. For hundreds of years houses in Norway have been covered with turf. And they come in different varieties. Some are bright green and almost velvety. Others are golden and look like they’re growing wheat or oats. A number of turf roofs have flowers mixed in with the grass, and a few have small trees.

For more.. http://www.amusingplanet.com/2010/09/grass-roofs-of-norway.html