Sagan Institute Box
Box constructed by a noted American institution named after Carl Sagan, designed for the occasion that Earth could somehow, hypothetically, get the box to a distant world.
The box contains information pertaining to the people of Earth, extending a hand of friendship. The box also included a sample of iridium, a distinct nuclear signature Samantha Carter had installed. This would make the box detectable in the event the box was ever returned.
Thor's Hammer - Jackson gives the box to Kendra in hopes that Thor and his people will return to take it.
Thor's Chariot - Gairwyn throws the box through the Cimmerian Stargate where it impacts Earth's iris, leaving a detectable iridium signature.