grass blanket

flat grass would be similar to the upcoming moss/moss blanket but you would not be able to see it pop out of the ground like the moss. instead it would be flat and it would look like it was part of the texture of the block you placed it on. it would probably be 3d but be thin enough to look flat. it would be able to grow naturally on grass and near where sand and grass meet. you would craft it with either one grass block or 4 grass (with the grass block you would get the grass blanket and one piece of dirt).

The blocks you would be able to put it on would be:

grass (side or bottom of block)
all sand (when placed on sand there would be grains of sand on top of the flat grass)
gravel

this block would be good for maps and decoration