It's probably best to set up training situations rather than trying to do all this when the situation may be fraught or tense ;)
Choose items at first that the dog isnt too bothered about - for example many dogs will pick up their own toy and then give it to you, or on the floor, if you are going to throw it or tug it etc. YOu can start in a basic way by rewarding him when he does this, for high motivation and teaching use really tasty treats - chicken, sausages, liver. NOT just biscuits unless he happens to be a real biccy lover

Then, give the toy back or throw it, repeat this lots, and in the meantime keep household items out of reach. (Yes easier said than done, but you must!!! )
Have little happy sessions several times a day - if he growls totally ignore him. But do make sure you are not making him feel threatened, keep body language friendly, approach side on, smile. Happyvoice.
If necessary, if he doesn't play or doesn't give up anything, just give him something not too worrying - low value, maybe a sheet of newspaper, and when he does eventually drop it, say, "Good, Drop" and give the treat immediatley. Its imporatant he doesnn't think you are coming to get him when you reward him, so if necessary, chuck it near him.
After some time he will realise he gets nice rewards when he drops, and it will be possible to gradually bring the training on to more items of high value to him, socks or whatever he grabs most. Eventually he will give up stuff, and after some time you can just reward intermittenly.
Having said all this, it is not easy to convey everything via email and my sincere recommendation would be to get in a reputable behaviourist, (your vet could advise) esp. in view of the fact that he reacted strongly. It would just make it a lot easier for you and him, as you could be actually shown and the B. would come to your home and advise. There is a slight risk that if you do choose to sort him out yourself, and do the wr0ng thing accidentally, he may get harder to train out of this :)
LIndsay
Just checked out where you live, I know an excellent trainer (not behaviourist but he's very good) in Fife :) Let me know if you want his details. Hth.