I think i've managed to clone out the blade of grass. Since I am using a Dutch version of Photoshop CS, I'll try to explain how I did it.
I selected the tool which you can find just above the clone stamp. (looks like a band aid) Set it to 26px (could have been less) 49% (hard) 1% spaces. I selected (Alt) severall different spots close to the blade (color like) and got the result in a few seconds.
I hope this helps. Could you do me a favor, and give me the correct English names for the steps I took?