Symbolism, Imagery, Allegory
Don't Boar Us with the Details
Llewelyn Moss wears a boar's tooth on a gold chain. It's one of the first details about him we learn: "The boar's tooth he wore on a gold chain spooled onto the rocks inside his elbow" (1.3.7). Later, when trying to decide what to do, "He stood fingering the boar's tusk at the front of his shirt" (1.3.37).
And that's really it; the boar's tooth is barely mentioned for the rest of the book. So why mention it in the first place? Well, clearly the thing is important to Llewelyn. Maybe it comes from the first boar he killed, or maybe it came from a hand-to-hoof death battle with a particularly gnarly boar. We'll never know.
This makes the boar's tooth the opposite of Chigurh's coin. Chigurh can't shut up about his stupid coin when he pulls it out. Llewelyn, however, never talks about his boar's tooth. And while Chigurh thinks of his coin as an instrument of fate, Moss believes more in luck. He just rubs it a little when he needs a little extra courage, or something.
Considering the fact that Llewelyn Moss dies, either there's no such thing as luck in this book, or his boar's tooth turns out to be bad luck.