I know it's the opposite of what you want, but how about incorporating bitcoin into the wedding favors. I know match books are out of style but something similar with a paper wallet printed on it would be nice.
I like this idea the most, you can generate paper wallets with custom backgrounds (i.e. nice engagement photo of you both), so it is both a souvenir from your wedding and an introduction to bitcoin. Then you need to include instructions on how to create a blockchain.info wallet and sweep the private key from the paper wallet.