My question involves criminal law for the state of: Virginia

I purchased about $55.00 worth of clothing from GAP Kids and when I was leaving stuck a $20 shirt in my bag. I was not stopped when I left the store nor were there any cameras in the store. Now I just feel horrible about what I have done, the guilt is killing me. I'm not sure why I acted out the way I did. I made a horrible mistake. I am worried that they will look up my credit card information and come after me, and that there will be a cop knocking on my door any minute. I want to return the items but am to ashamed to go back to the store. Do you think it would be a good idea to mail the items back with a note?