Step 01:
Open a new document sized however you would like. I chose 512x192 with a transparent background. It doesn't matter what background color you choose, you will cover it completely in the next step.
Step 02:
Choose a blue color as the primary color and a light color of the same tint as the the secondary color. Using the Gradient Tool, create the basic colors of the sky. I chose a Radial Gradient for mine.
Step 03:
Now its time to add some clouds to the sky. There are various methods of doing this but I used some cloud brushes I downloaded from DeviantArt. You can scatter them in any way that looks good to you. Its hard to mess this part up.
Step 04:
Probably the most important part of the image is the grass. Fortunately, its one of the easiest parts. Photoshop includes a really good grass brush in its stock brushes. After pulling out that brush and selecting some different brightness greens, begin to apply the grass. You can really go free here.
Step 05:
I like to make the brush smaller for the parts that are far away and larger where its closer. You should also start at the top and work your way down. This makes the brushed cover the base of each other.
Step 06:
This really is required, but I think it looks good. I darken the greens and scatter some more grass around. It adds some more color and brings the appearance of shadows.
Step 07:
This is the last step of this tutorial. It too is not really required but I think it gives it a good look. I add a Lens Flair from the Filter > Render menu. Its best to angle the flare so that the light is coming from the brighter part of the sky, but I didn't. I was in a hurry.
Well thats it. I hope you guys enjoy this. If anyone does decide to try it out, I would love to see some of your outcomes posted here.