Just a warning to take care when out detecting. A grandad and his grandchildren were having a day out metal detecting in a Devon field recently. Upon getting a good signal he dug down and thought there was an old silver ring in the hole. As he pulled the ring he realised it was attached to another object.
After a quick inspection he realised he was holding a live hand grenade in his hand. The full story can be read here
I think there are a couple of lessons to be learnt here the first is be extra vigilant if the site has the slightest evidence that munitions could be there. Secondly do not take you children/grandchildren to a site where munitions could be buried.
No find is ever worth losing a hand, leg or life over.