None, such crowns are all copper-nickel and run about $1 in uncirculated condition.
one pound
You most likely have a gold and silver plated 1965 (copper-nickel) British crown (5 shillings) these are incredibly common and the gold/silver plating adds no value to the coin. Your coin is worth 50 cents to a dollar or so.
99 pence
Modified coins have no collector value. Any value the pendant may have would be as a piece of jewellery. The coin itself might get up to £2 GBP if it was in mint condition and had not been silver plated.
Try eBay or a reputable coin dealer. They do not have all that much value , so do not go to too much trouble. British 1965 Crown - Churchill commemorative.
US dimes from 1965 to date are copper-nickel not silver. The coin is face value.
The Royal Mint did not produce a 1965 rhodium plated 24 carat gold Churchill Commemorative coin. Any such coin would most likely have been privately minted and would only achieve the value of the metals used, maybe a little more.
None, it is made from a copper/nickel alloy. There has been no silver in any British general circulation coin since 1946.
The 1965 'Churchill' Crown was mass produced in 1965. 19,640,000 were struck in cupro-nickel (an alloy of copper and nickel). They are worth today (September 2010) between 50p and £1 depending on condition.
No quarters have been made in Delaware. No US coin dated 1965 has a mintmark or any silver in them, the coin is face value.
The "Churchill Dollar" more correctly known as the British 1965 Crown (Five Shillings) Churchill Commemorative coin is made from a copper-nickel alloy as have all circulating British "silver" coins since 1947.
The 1965 Kennedy half dollar is a 40% silver coin (1965-1969) but so many were made only a very high grade uncirculated example is worth more than the silver in the coin. The silver value today is about $2.70
US circulation coins prior to 1965 were made of coin silver, not sterling silver. Coin silver has more copper in it for hardness, so that the coins wouldn't wear out as fast.