I'm looking for some pieces of natural stone like shale and slate that I can use in a little landscaping project. It needs to be flat and each piece should be at least a few square inches, but otherwise it can be any color, shape, and size. Ideally I'm looking for broken up fragments from someone's natural stone construction project. I want to put them between some plants and don't mind funny shapes. In total I'm looking for about 10 square feet of material in total.