The World of Mathematics edited by James Newman (a four-volume anthology) may give you a feel for and an interest in exploring math further. It's a great collection ranging from mathematical curiousities and puzzles to memoirs of mathematicians to a very moving short story by Aldous Huxley. Also, One, Two, Three, Infinity by George Gamow (a great physicist) is a great intro. Second the How To Solve It recommendations.
Also recommended in this reply