The grass block.
http://www.minecraftwiki.net/wiki/Grass_Block
Uses[]
64 grass can be used in the Industrial Centrifuge to produce 32 sand, 2 clay balls, 4 plantballs and 2 compressed plantballs.
Grass is a vanilla minecraft block, which covers a large portion of the surface of a randomly generated world. When it is broken, it drops a Dirt block. It mainly covers the floor of biomes such as Forest, Plains, Swampland, Jungle, Taiga (under the snow), and Extreme hills.
It takes 0.75 seconds to break one grass block by hand, 0.4 seconds with a Wooden shovel, 0.2 seconds with a Stone shovel, 0.15 seconds with an Iron shovel, and 0.1 seconds for both a Gold shovel and Diamond shovel, so if you are looking for speed, choose Gold or Iron, but if you are looking for endurance AND speed, choose Diamond.