Recently I found this PINCHme site that upon subscribing offers you two free sample that they hope you give feedback on but is completely unnecessary. Note that you will need a cell number they can send a text to with a verification code: Log In
I signed up with Pinch.me a few weeks ago. The samples they give out are pretty decent. My latest free sample from them was Post Honey Bunches of Oats Greek Honey Crunch. All their stuff seems to be from companies that are popular, no "mystery" samples so far. They also send out the free samples fairly soon after I request them.
