You need to provide the year. Without knowing the year it is impossible to value your coin. Crowns (5 shilling) pieces were minted in several different years and have vastly different values depending on what year they were minted in.
The Royal Mint did not produce any Five Pound coins of any type from 1938 to 1979 inclusive.
The first British general circulation decimal Five Pound coin (Crown) was issued in 1990.
The first British gold decimal Five Pound coin was issued in 1980.
Such a coin does not exist.
The last British Five Shilling coin (Crown) was minted in 1965.
There was no 1956 British Crown (Five Shillings) minted.
There was no 1963 British Crown (Five Shillings) minted.
There were no 1823 British Crowns (Five Shillings) minted.
There was no British 1907 Crown (Five Shillings) minted.
There was no 1923 British Crown (Five Shillings) minted.
A Halfcrown is the eqivalent of Two Shillings and Sixpence. A Crown was Five Shillings.
There was no British 1886 Crown (Five Shillings) coin minted.
There was no British 1846 Crown (Five Shillings) coin issued.
what is the value of a Jamaica five shillings
There was no 1955 British Crown (Five Shillings) minted. You possibly refer to the 1953 "Coronation" Crown.
The Royal Mint produced no British Crown (Five Shillings) coins from 1938 to 1950 inclusive.
A British 1929 Crown (Five Shillings), uncirculated and in absolute mint condition could fetch up to £425 GBP. If it has been circulated but still in good condition, it might fetch anything from £85 to £250 GBP. A reputable coin dealer will be able to give a more accurate valuation.