I desperately need cropping freeware that only crops the subject of the photo so I can put on white backgrnd?

Any idea on where to find an easy one to work with? I don't need to crop an exact ratio (i.e. the squares and rectangles people usually think of when they crop a photo.) I need to crop the SUBJECTS of photos only. I've found Photo Crop Editor, but it's really unrealistic for the amount of extra work involved. I want something that finds the borders of a subject automatically, or at least lets me do it manually without too many steps. Must be freeware because the work is for a charity org and I don't need to tell you how their budget probably is....thanks for any help!