Value of 3 cent piece

It depends on the date, condition and the type. There were two main styles of three cent pieces, there was the 3 cent silver which was tiny and the 3 cent nickel which was large (the 3 cent silver had a star on the obverse, the 3 cent nickel had a head of Liberty on the obverse). Without knowing the date or at least the type, it is impossible to answer your question.