Whats this?
 

Window molding fell off of 2012 Buick Lacrosse. Any idea what this clip is called and if it cam be replaced?
https://cimg3.ibsrv.net/gimg/www.bui...6493c5ec8f.png

Sometimes you might find them in a regular auto supply store.
The places that use them most are body repair shops (molding retainer clips).
Dealership parts dept is a good place to start. They are what are called , speciality or dealer items.