I would like to help you. But, ethically, I don't think that would be a wise choice on my part.
I would suggest checking out the information that you might find on the following site or take it to a pharmacist for identification and disposal. The site below is good, but not foolproof. But, to be sure, I would take it to a pharmacist. Anyone answering you here runs the risk of the ramifications if they answer and are incorrect no matter what you say the reason or reasons are as to why you are asking.
Below, is the site to which I am referring: Pill Identifier - Drugs.com
I don't know what the pill is. I don't know you and you don't know me. I could say the pill was something that it is not. What might happen next? You confront your son because someone here saying they were sure of what the pill is? What if the information you have been given here is incorrect? You've already been given three different answers above. Maybe the pill is something harmless? I don't know. What if you decided to believe what I said is true and then you take the pill even though you say that you think it is for someone else? What if I was really wrong and the pill could turn out to be something deadly to you if you took it, or you said that you asked an "expert" on this online site who said that they were really sure of what the pill was and that you should not worry about going any further with trying to identify the pill? There are people who answer that way on this site. Please see information about that on the following link if you have any doubt as to people actually acting like theirs is the last word on the identification of a pill. http://www.askmehelpdesk.com/medicat...ll-144678.html
Reliable pharmacists are usually very easy to find around where you live, and can visit with you and see the pill first hand.
I'm not a pharmacist and I'm not going to pretend that I'm some sort of expert at identifying pills. So, unless someone is a pharmacist here and has actually seen the pill that you have found and is truly sure of the reason or reasons as to why you are asking, even though they are trying to be kind and think that they are answering in your best interests, it is not in your best interests or in the best interests of any person here who thinks that they have the correct answer for you because of the possible ramifications when being incorrect when giving out such information.