Very few places have free stuff available, and those that do are usually low-res copies of their higher resolution products for sale.
As a side note, be careful of stuff that people might give you or that were taken from a school or firm library. They often carry licensing agreements that can get you in trouble if someone who knows what they’re looking for sees them (for example, ImageCels stuff stands out in it’s look from other image packs, at least to me it does). Your best bet is to start cropping things out yourself and slowly but surely build a strong library on your own. Who knows, someday you might be able to sell the next greatest set of entourage images…
Probably not the answers you were looking for, but theres my experience in a nutshell.