This is a very cheap solution that looks pretty good; so if you are looking for fancy and expensive, you've come to the wrong place! But, if you are like me, and budget matters, then just maybe this can be an inspiration for someone.
First I purchased 3 "manufactured panels" from a local hardware store, 2' x 4' each. These are basically boards that are manufactured from pressing wood pulp into a form -- so it will not have any wood grain, even though it is wood. I also obtained some very cheap spray paint -- one white and one gray. (This is the 99 cent variety you can get at Wal-Mart, etc.) [Insert standard disclosure here about spray painting in a well ventilated area, using a mask, etc.]
I sprayed each panel on one side, first white then gray. I did not spray evenly, as I wanted an uneven look. It's OK for the gray to be somewhat clumpy. I let it dry for several hours.
The product I used for the green color was "Minwax Express Color" -- which is a water based stain and finish in one. In other words, once it dries it has both the color and protection. This was important to me, because I have spilled on the table before (with 4 year olds, this isn't uncommon!). Like I said, I'm using it on fake wood, which doesn't have a grain, so I can't really comment on how the product would work on real wood.
Since it's water based, there isn't much odor, and it drys fast . . . REAL fast! In fact, I think it would be a little easier to work with if it didn't dry so quickly. You have to do small segments and work efficiently. These two globs lead to this:
The product info says "a little goes a long way," but I think that's a bit of an exaggeration.
Repeat until covered as desired. Note, it does come out pretty streaky (which is what I wanted, to simulate a field of wild grass), so be sure to wipe the product on in one direction.
I let dry for at least 24 hours.
I have two inexpensive saw horses in my basement. (You can make these yourselves with 2x4's). I laid across them two boards that are just under 6' long.
So here is the finished product! I can't figure out why the leftmost board is noticibly darker than the other two. My best guess is because I did them on different days, and the day I did the leftmost one was colder and more humid than the others. (It's exacerbated in the picture by the flash.)
With some random terrain.
This last picture is without the flash.
Hopefully some games & reports to come!