You need to set the tag property of the card. Whether at run time or at design time. If you look at the card's properties, at the very bottom you'll find the tag property. I set the tag as an Integer, but really it could be any object(String, Boolean, etc.). Here is a picture of where to set the tag property at design time:
Name: tag property.png Views: 187 Size: 63.0 KB

If you wanted to set the tag property at run time, the code would look like this:
Code:
fooPictureBox.Tag = fooObject