Help! Aggressive puppy. Only 4 months old.?

She has been like this since we got her 2 months ago. She gets possessive aggressive over things. It can be anything from a sock to a piece of plastic she finds on the street when out walkies. She will growl and try to bite us, drawing blood on many occion. Recently, she has even started doing this over other things like being put in her crate or getting off the furniture. You name it I've tried it. I've got to the point that I what rid of her but am scared her new owners will have the same problem and will move her along again or use harsh methods to train her. A lot of the techniques I have tried made a small dent in her behaviour giving me hope but she wised up to them and we're back to square1. We have tried some Cesar techniques, trade up with toys and treats, being more forceful in the voice etc. There's more things we have tried but there's so many I can't think of them right now. PLEASE help. It's either something that works or she's gone. When she is nice she is so loving.