In the 4th season episode "The Curse," Dr. Jackson's mentor dies. The mentor's name is Dr. David Jordan (1). Going back to his alma mater to pay is respects, Jackson meets up with two former colleagues: Steven and Sarah.

It seems the dearly departed archaeologist was examining artifacts from the Stewart Expedition (2).

Steven, who despises Jackson for some reason, is surnamed "Rayner." (3) Sarah, later becomes the host to Osiris, is surnamed "Gardner." (4)

For those Green Lantern fans out there, that's 4 Lanterns named -

Dr. Jordan - Hal Jordan

Steven Raynor - Kyle Raynor

Sarah Gardner - Gil Gardner (I think)

Stewart Expedition - John Stewart