Crowns were not issued in the time of Edward I.
It's impossible to say for certain, as the question omits the coin's denomination. A silver coin for that year could be a threepence, sixpence, shilling, florin, or half crown.
CHILDEN
Such a coin does not exist. The Royal Mint produced no 1704 Crown coins.
A British 1902 sterling silver Crown (Five Shillings)(Edward VII), uncirculated and in absolute mint condition could fetch up to £265 GBP. If it has been circulated but still in good condition, it might fetch anything from £60 to £175 GBP. A British 1902 sterling silver Crown (Five Shillings)(Edward VII)(Matt Proof FDC), uncirculated and in absolute mint condition could fetch up to £225 GBP. NOTE - The 1902 British Silver Crown was the only Crown coin minted during the reign of Edward VII. The values quoted are the best possible for the best specimens in their grades, but may be significantly lower due to varying demand for the coin and the prevailing economic climate. A reputable coin dealer will be able to give a more accurate valuation based on inspection of the coin.
The 1950 Half Crown of Georgius VI is not made of silver, but of cupro-nickel. 50% silver Hlaf Crowns were issued until 1946. Source: Wikipedia
If the candelabra is sterling silver and marked with a crown, the value could be as much as about 600 dollars. The FB Rogers Silver Company in Taunton, Massachusetts released a large number of these candelabras and the value does follow the silver market.ÊÊ
$50.
1959 Bermuda Crown: On a purely Scrap silver basis at today's silver price (27/03/2013) its £15.89 (28.28g of .925 Ag).The 1964 Bermuda Crown is £6.87 (22.62g of 50% silver).Obviously collectors may pay much more for coins in good condition.
It depends on the condition, but if circulated the coin sells for scrap silver (it is 50% silver) about $8 at the time of writing.
150 dollars
All Peace dollars have this. It's just a normal part of the design and adds nothing to the value.
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.