A good tool for creating a nice looking grass is VrayFur. Though not very realistic, it is enough for this type of scene. I created three VrayFur objects with the same Source object, of various colours, length, thickness, gravity and distribution, to add some diversity.
Texturing was the most important part in creating this scene. My aim was to create realistic, dirty, old textures whilst retaining the nice and pleasant character of the picture. For the whole scene I used the 3DTotal Textures Collection: Volumes: 1, 2, 3, 5, 12, and 13 in particular.
The texturing process is different for every object and depends on things like size, visibility/exposure of the object in the scene, the type of material etc. However, there are few general steps to follow when texturing objects for scenes like this one. I will try to explain these below:
The first step is to always map your model. Sometimes it is quite boring, but it is crucial for the next process. It is difficult to texture poorly mapped objects, so it can save you time in the future. Unwrap UVW is a great tool when you are familiar with it. It is important to remember that in a static scene a model is only partially visible. So I select invisible polygons and unwrap only those which are important for my picture, it can save a lot of time. Another thing is to place polygons on the texture in the right way in order to simplify texture preparation. I always try to work on parts of polys which are as large as possible, choosing large flat areas to avoid dividing them into small parts. Fewer seams mean easier texturing. I also try to keep the same scale for all polygons on my texture and not waste space. Try to use different methods of mapping; flatten, unfold and all types of normal mapping from Edit UVW menu, and from Map Parameters: planar, cylindrical, spherical, etc.
After unwrapping the model, I often 'bake' to texture something like ambient occlusion. It is useful, especially for old and dirty objects. I use Scaneline renderer with Light Tracer and Skylight light to bake it. First thing is to change the material to standard and set the diffuse colour to light grey, then place Skylight in the scene ant set its colour to white. Turn on Light Tracer and tweak settings to speed up rendering. You do not need to obtain excellent quality because you will mix the texture with others.
This is the first time that you have to think about the size of the texture, which depends on the size of the final rendering and the size of the object in the rendering. You can of course resize the baked texture later, but not too much. A nice thing in 3ds max 8 is rendering UVWs in Edit UVWs. I always render black lines on white background without Seam Edges.