Your boss and co-worker sound like terrible people.

Just report it, call the police, something. Don't roll over and take it. This is ridiculous behavior from coworkers, especially bosses. Absolute bull.

report him for theft

Go to HR and speak to them. You are the rightful owner and can go to the police. Then start looking for a new job. The boss will make your current one hell.

I don't understand your desk mates thinking... oh a cookbook on my shared desk! It couldn't possibly be my deskmate's.

just wanted to throw this out there but your boss and co worker committed a felony. theft of anything over $50 is a felony... so... they might want to return it. also who in the hell just picks something up at work and regifts it? There would've been an excellent possibility of it being someone else's property.

Why would your desk mate give away something that he knew wasn't his, just because he didn't know who it belonged to?

I would go over your bosses head and report him as well as your co-worker. That creates a hostile work environment. (Grounds for firing.)

I feel like I just read a summary of a Seinfeld episode that was never actually made.

Go Over Your Bosses Head, Get The Co Worker To Back You Up That It Was A Gift.