I've been given the task of splicing two graduation photos together. The main problem being that the backgrounds are too different to merge/blend at the join so I would like to cut them both out and paste them onto another background such as the 'bookshelf' one that I have seen on numerous school photos. Where can I source this from or other such academically themed backgrounds?

Try http://www.morguefile.com/ or http://www.sxc.hu/

I've found just the thing, thanks!