HI there,
To be honest i am uncertain from reading your post as to whether your pup is in fact playing, (which can often sound quite scary

) or whether there is a problem, and it is very difficult to tell from an email.
Do you actually play WITH the puppy? As if you just give him toys he will get bored amusing himself and be desperate for a game with you, or another dog. This could possibly explain the pup's reacti0ns.
I am feeling this is more the case, because you say that normally he is very sweet, until near his toys. I suspect the growling and attacking is his idea of game.
If this is the case you do need to control the pup as it can't be allowed to carry on. I would recommend training classes, visit a few and start attending the one you gel with best :)
Look for a class which teaches sensible basics such as "Give", "Leave", "Drop" etc. I would also recommend getting a few good dog books to help you understand dog behaviour, and why dogs do what they do. Try John Fishers books, such as "Why Does my Dog..?" or "Think JDog" from www.crosskeysbooks.com or anything similar. Also do get a copu of the brilliant "The Perfe
ct Puppy" by Gwen Bailey, this is really good commonsense reading and will help to give you confidence.
Pups do mouth and nip expeciallly when over excited, but it does need to be controlled and eventually extinguished. For the mean time, re-direct the pup's excitement onto another toy you can control. If the pup bites you, end any contact or game at once and don't speak to or go near the pup for a few minutes. This will start to show him that rough play equals end of the great game. Also play constructive games with him and start teaching him to Give or Leave by using2 toys. The Puppy book mentined above will help with all this.
Hth a bit
Lindsay