Grass is a standard block that is commonly found directly above the uppermost layer of Dirt, but can also be found directly above Stone, or even floating (unattached to anything). There are two variations of the Grass Block: the Flower Block and the Weeds Block. These two Blocks appear less frequently per chunk than the Grass Block, and the Flower Block was removed with Update 2.0.
Grass is the most common natural block per chunk after Stone and Dirt.
The lower two thirds of the Grass block are a variation of the Dirt texture.
The Weeds Block looks nearly identical to the Grass Block, though the only difference is the texture on the top.
The dirt texture underneath the grass has a slightly lighter tone than the Dirt block.