In The Hobbit, in chapter 2: Roast Mutton, there's a scene where Bilbo sneaks up on some trolls. Rather than go back and warn the dwarves, he attempts to pickpocket one of trolls before he does.
From p. 47 (of my copy, at least, the Alan Lee illustrated version):
Bert and Tom went off to the barrel. William was having another drink. Then Bilbo plucked up the courage and put his little hand in William's enormous pocket. There was a purse in it, as big as a bag to Bilbo. "Ha!" thought he, warming to his new work as he lifted it carefully out, "this is a beginning!"
It was! Trolls' purses are the mischief, and this was no exception. "'Ere, 'oo are you?" it squeaked, as it left the pocket; and William turned round at once and grabbed Bilbo by the neck, before he could duck behind a tree.
So, it appears that the purse itself says "'Ere, 'oo are you?", given that "it squeaked, as it left the pocket". Does that mean the trolls had a magic purse?
Also, the fact that the tone of voice the purse spoke in sounded rather "trollish", meaning "commoner-like" rather than more "well to do", this implies that the trolls might have even enchanted it themselves, or at least altered the enchantment themselves. Not only that, but "Trolls' purses are the mischief" is said in a way that the narrator (Tolkien) is implying that this is apparently well known about trolls, which further suggests that the trolls might have enchanted it themselves.
Is this right? Do the trolls have a magic purse, and is there any further evidence to suggest that they enchanted it themselves?