Needs pictures of faces with neutral expressions and neutral lighting?

I'm doing a research project on facial symmetry. I'm showing an original face and then a symmetrical copy that I produce with photoshop and having the participants give ratings between the two. I need about 6 faces (3 men and 3 women) with neutral expressions and neutral lighting (no distinct shadowing on either side). I'm having almost an impossible time finding photos that are not copyrighted. Does anyone have a clue to where I may be able to find some that I can use?