The first thing to check is the column format you are storing the symbol into - it should be NVARCHAR not VARCHAR as the former is Unicode and the latter is not (assuming you have MySQL 5 or above)
Then, there is the transfer of data into the column: if you are concatenating strings to form your SQL statement then you need to prefix the string constant with "N" to indicate that it is already National Character Set data:
INSERT INTO MyTable (currency) VALUES (N'£')
If you do it via parameterized queries (as you definitely should be anyway to avoid SQL Injection Attacks) then that is handled by the system automatically.
Reading out should be no problem: once you have got it in it should "just work"