If you are finding for a icon collection free, then Citric Icons (free PSD, as usual) is ideal for you. Treat yourself to this collection of Free Citric Icons (free PSD, as usual) created to help you develop great UI projects.
Download royalty free icon file and use it as you wish to use it. This freebie has been provided by Dribbble.com.
If you want more icon, you can check the Free Icons.