Possible to create flat, grid terrain with 3D objects on it?

I'm wondering if there's an easy way to create terrain that is based on a grid, with each square of the grid representing a different terrain type, such as grass, mud, etc. I would also like to be able to place 3D objects on top of the terrain, and be able to move my character around on top of the terrain, and amongst the 3D objects.

I'm looking to do a simple top-down puzzle-style game with a flat map, but still use 3D objects to represent elements in the game and the characters themselves. Just wondering what the best way would be to generate these types of terrains...