VISIT MY BLOG FOR BIGGER SCREENSHOTS!
If I had to describe this method of making grass using the infamous "design triangle", I'd say it's "cheap" and "quick". Therefore, I cannot guarantee the highest quality straight off the bat. However, sometimes you just need to cover some ground. If you don't want to spend ages on googling images only to find ones that everyone's used (and seen) hundreds of times and/or you need a very particular type of grass - this tutorial is for you.
DISCLAIMER
I'm showing a very speedy version of this method. There's some horrendous stuff in my textures (like no padding, wasting space etc.) that I'm aware of. For this project I needed somehow decent looking grass ASAP, without taking stuff like performance into consideration, so I had to choose my battles. As this workflow is quite simple and highly editable, it's up to you to tailor the following steps to achieve the quality you need. Enjoy!