Rattling noise when my engine is running?

Is 2000 Toyota Camry worth repairing? Leaking oil bad, cut it off as soon as it made a noise. Seal broke?
This car has 200,000 miles. Ran great and was very dependable prior to this. Is it worth fixing? Is it worth fixing or should I try to sell it for parts (there are tons of these cars on the road)? The a/c, cd/tape/radio, power windows and doorlocks, power seat, entry fobs, etc. Work perfectly. What course of action should I take to make a dtermination on what to do with this car?. It is too good to just junk!

Cylinder head picture

This first happened when I stayed overnight in a motel and the temps got cold, in the teens. The next few winters it only happened in the morning after a cold night, garaged. It gradually got worse and now is loud on start-up, all the time. It is almost like a growl and/or rattle. And it almost sounds like something is loose. Within a minute or so, the loud noise is gone. I've been told to not worry about it, but it sounds like I'm driving a junker. Plus, I'd like to get to the bottom of it & get it fixed.