yes. if you keep them they're not taxable, but if you sell them for the currency of your country, they are.
Are you sure? The IRS pages linked above suggest that merely receiving bitcoins would count as barter income and so is taxable at its market exchange rate to dollars
If you're growing say cucumbers in your backyard and pickled them for storage. How would your taxman view that? Logically it seems to me that if you're not selling away your pickles, then there's no tax. But if you start selling them or trading them regularly on significant volumes, then there might be a tax.