One of my favourite types of fic. I've got a few I'd recommend:

Stanford:

And They Cry To See Your Face (http://ohsam.livejournal.com/268016.html?thread=1805296#t1805296) - Some of Sam's college buddies get rescued by him and Dean, but he's not the man they knew anymore.
Days Dawning; Pure Morning (http://rememberbefore.livejournal.com/30807.html) - Sam's college roommate, who did notice that Sam stole the salt shakers from the dining hall, among other things.
Davil's in the House (http://glorious-spoon.livejournal.com/5556.html) - In which Sam hust ()les pool to pay for his textbooks, and an unexpected opponent turns up.
Five Times Jess Wondered About Sam (http://archiveofourown.org/works/11872) - Exactly what it says on the tin.
If These Walls Could Talk (http://vorpalblades.livejournal.com/16945.html) - A janitor goes through Sam's room at Stanford.
Last One Standing (http://archiveofourown.org/works/101289) - Becky hears about Brady's death.
Let Me Tell You My Thoughts and My Visions (http://kiwiana-inked.livejournal.com/4677.html?style=mine) - In which Sam and Jess move in together, and Jess realizes that Sam has some unusual habits.
Lies were kept simple (http://hells-half-acre.livejournal.com/2196.html) - Jess has her suspicions about Sam's family.
Like Chocolate and Toasted Marshmallow on a Graham Cracker (http://spoons1899.livejournal.com/137412.html) - Sam and Jess go camping, Sam doesn't know how to make smores, and Jess knows there's something dark in Sam's past.
no one knew me, look right through me (http://rememberbefore.livejournal.com/27717.html) - There are some things the kids at Stanford knew about Sam Winchester, and some they didn't.
One Sang High and the Other Sang Low (http://kroki-refur.livejournal.com/103813.html) - Dean shows up, Sam hunts a ghost, and Jess decides that Sam's relatives are gypsies.
Outsiders (http://idlehands.ponderosa121.com/outsiders/) - Sam's college buddies gossip about him after he leaves.
Through the Grapevine (http://ficwriter1966.livejournal.com/47428.html) - More gossiping.

Law enforcement recs coming later.