if you have very good condition (i.e. min condition) from early years they might be worth something. the "capital cities" series (which i cant say i ever saw) are worth something as are a few of the other intersting designs. generally though you'll have to wait a lot longer than 10 years for these to be worth anything significant. example, a Victorian crown in good condition is worth around £20, which has about £12 of actual silver (though one in "fine" condition will be worth double).
The four City set(London, Belfast, C ardiff, Edinburgh) of round pounds are selling on Ebay, in circulated condition for up to £26 at the moment, not a bad mark up.