There are now £5 coins which are considered crowns, as 25p was a little too little, though you can get the £5 coins for £5 from the mint, which is what I do, and then they are supposed to go up in value to about £6-8 after a few years.
They have made one every year for the last 15 years or so I think, I started getting them since 2002 when I realised the post office sold them, now they don't but with free shipping, always worth getting, if you are in the UK at least.
I also have the 1933? coin from George V 25 anniversary of his coronation, though not in silver as it was, not sure if it is a fake, a test piece or what, but it was cheap and looks good. Need to get a real one. Crowns from the UK are collectable I think, though other countries do them like Aldernay, Gibralter and they always have really bad designs.