I have a very uneven back yard, from a combination of settling, bad maintenance, and a very enthusiastic dog (digger) that a previous owner kept out there. As part of a large backyard landscaping project, we will be flattening this lawn and growing clover instead of grass.
My current plan is to fill in the low spots and spread a couple inches of soil over the whole area (~75' x 35'). I'll cut the grass as low as I can, but will there be problems from leaving the root systems in place? I've considered renting a tiller or power rake, but I'm worried about destroying a rented tiller, and I'm not sure how deep a power rake is going to get. There are plenty of mid-sized rocks and hidden concrete pavers out there.
Update: my big concern is what will happen to the soil itself with a layer of dead grass underneath. I'm not as concerned with some grass growing up through the new top layer.