To be more specific, it's a machine-struck, mass-produced replica of an ancient Judaean lepta, the coin called a "mite" in the King James version of the bible in the story of the poor widow, who gave "two mites" to the temple treasury.
The design is rather crude, and appears to have been created by copying a picture or rubbing of a coin, rather than copying from an actual coin.
As for value, not much. They are sold in bulk by religious supplies stores, for churches, Sunday School classes etc to give away as a tangible sermon or bible class illustration.
Here's a seller on Etsy who will sell you a packet of 50 of them for US$14.
Because they're so common, and because they don't normally come in wrappers explaining what they are, they are one of the most confusion-causing replicas around today. We typically see one here on the forum every few months or so.
Genuine "widow's mites" are fairly common, but not very cheap; as with any coin actually mentioned in the Bible, their value is five to ten times higher than an equally rare coin that is not so mentioned.
Here's an ebay seller offering average-quality examples in bulk quantities for US$40 each.
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