"30091" is not a ZIP code; the USPS did not invent ZIP codes until 1963, and these tokens usually date from before this time.
This thread has a token identical to yours, but the number there is "21197".
And this thread has a larger holed token with the number "4461".
I'm not quite sure what the numbers are, but I would assume that they're control or reference numbers for the manufacturer of the tokens, so they can either match token types for different customers, to keep track of dies etc.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis