Aiken has had stints with the Bears, Patriots and the Bills but has yet to log an NFL statistic in a regular season game. He attended college at Central Florida.
Buckner and Hawkins have both previously been with the Cardinals, with Buckner also spending time with the Buccaneers at one point. Sims had a previous stint with the Patriots.
Vandenburg spent time previously with the Vikings and Stephens has been a part of both the Titans and Cowboys previously.
None of these receivers appear to offer anything substantial and would appear to be practice squad considerations and not long-term options. The quarterbacks were likely brought in to work out the receivers.
UPDATE: Aiken and Stephens were signed to the practice squad after the Ravens released Michael Huff and Marcus Spears. The practice squad positions came open when the Ravens called up Omar Brown and Brynden Trawick to fill the open 53-man roster spot.
In order to provide our users with a better overall experience, we ask for more information from Facebook when using it to login so that we can learn more about our audience and provide you with the best possible experience. We do not store specific user data and the sharing of it is not required to login with Facebook.