I add a link to my portfolio (on an online drive) on my resume. I worked (as an intern) for a company in the past but, I don't have an experience letter or a recommendation from them. I no longer work for this company. I list this experience on my resume though. Can I add the offer letter I received from this company to my portfolio (like an endorsement that I did work there as an intern for a specific period) ? This offer letter includes my hourly wages, bonus etc. I ask because, I don't know if recruiters would think it's weird or non-standard (this is in the US).
There are other things like diploma, transcript, merit certificates and recommendations that I have on my portfolio (in chronological order) already.