In Delaware County you can dispose of that stuff at Llanerch Landfill...it is an old quarry on Rte 1 that accepts clean fill. Haven't used them in a while so not sure what their pricing is, but it was fairly reasonable from what I recall.
Try mulching your leaves. As far as brush I use friends in the tree bus. to chip and haul away. If you want to dump expect to pay $32/1000lb. In montgomery county there are several places I know of if, you are a little more specific about your location I might be able to tell you where to go.
Try looking in the phone book under refuse or demolition.