The original game boy was only capable of displaying 4 shades of grey. FOUUUUUUR. However, the 2 1/2 inch screen meant that it was more like 4 shades of green.
Nowadays you can put Doom on an I-Pod...
Anyways, I made this on that many shades of grey, and the pallette is in the corner. They're 16x16 sprites, and I took the liberty of increasing their size to and placing them beside the actual sized ones so you don't have to press your nose to the screen.

If your interested, I made it after reading the tutorial here:
http://www.gas13.ru/v3/tutorials/sy.....grass_tile.php