I just got done jack hammering and removing an old garage foundation along with a large amount of blacktop in my backyard or should I say parking lot. It appears that the soil is clay and has some crushed stone mixed in with it. The yard area to be is about 1 foot below grade right now and I am not sure if I should just fill this area with dirt or should I get some type of crushed stone first to help with drainage due to the clay. I plan on putting a concrete pad in the corner and building a small garage on it and will be using crushed stone there, but should I buy extra? Im new to the whole landscaping field so any advise would be appreciated.