I am beneficiary of my sons 401k account he has passed away. what documents do I need to produce to recelve the benefits

I am sorry for your loss. A 401(k) account does not become part of the original owner's probate estate unless the estate was the actual designated beneficiary, so if you are actually the designated beneficiary, then no, the 401(k) account will normally pass directly to you and not through your son's probate estate. You will need to contact the plan administrator to find out what documents you need to produce. Generally, however, you will need at least a certified copy of your son's death certificate and a completed beneficiary claim form. You get the certified copy of the death certificate from the state where your son died, and you get the claim form from the plan administrator for the 401(k). The plan administrator will also tell you if they require additional documents.