Silas Marner?
Literary Buffistas 3: Don't Parse the Blurb, Dear.
There's more to life than watching Buffy the Vampire Slayer! No. Really, there is! Honestly! Here's a place for Buffistas to come and discuss what it is they're reading, their favorite authors and poets. "Geez. Crack a book sometime."
The Weetzie Bat books by Francesca Lia Block?
Roll of Thunder, Hear My Cry is written for kids that are a little younger but I think they would get it.
Would Pride and Prejudice or Emma work? They are girly/romantic, but simple issues, and possible movie tie-ins and discussion of real social issues, gossip, privilege, etc.
I am trying to think of what I read in 7-8th grade classes - not a lot of novels. Short stories. 9th grade we read Great Expectations, Romeo and Juliet, My Antonia.
Is she specifically looking for 20th century lit? How about Picture of Dorian Gray combined with The Turn of the Screw? They're both quick, fast read, fun and exciting, and the latter has a female protagonist (well, not necessarily admirable, but still) and has interesting things to say about ambiguous content / unreliable narrator.
Roll of Thunder, Hear My CryThis was one of my suggestions! Along with The Secret Garden and A Little Princess (haven't heard a response)
Pride and PrejudiceThey read it in 11th grade. My wife hates teaching, though, and the 7th grade teacher loves it, so maybe it could be negotiated.
EmmaLove it. Only Austen I actually don't despise. Don't know if 7th graders would get it quite as well, but worth suggesting.
My AntoniaMy Antonia might be a good choice...
Picture of Dorian Gray combined with Turn of the ScrewThey do Dorian Gray in eleventh grade along with Jekyll and Hyde (summer reading, so fast reads are good) which is an awesomely perfect pairing. I don't know Turn of the Screw, but I'll suggest it.
I don't actually know if she's looking for 20th century or American specifically. They do US history in 7th grade, so tie-ins can be nice, but I don't think its a necessity.
Peter S. Beagle's A Fine and Private Place, or The Last Unicorn?
Hah, my first thought was also "Roll of Thunder"! Is "Circle be unbroken" a sequel to that or something else? I don't think I've re-read them since middle school. Hmm. Westing Game? Might be too young.
Does True Grit have enough "literary heft"?
True Grit
I don't know, I've never read it! But I'll suggest it. Along with the Beagles.
I think Let the Cicle Be Unbroken is a sequel to Roll of Thunder, yes.