I am curious about good places like beaches to camp in Hawaii. I herd somewhere that camping on the beach is free, is there any truth to that?

Yes camping on the beaches is free. Camping is a way of life on the weekends for the locals and their families. You won't be alone !!!

I just got back from camping trip in Hawaii.
There are few beaches allow you to camp but you need to get permits before you go.
Some beaches are not really safe(I've heard some local people beat visitors up!)
but I didn't have problem and camping is fun.
I recommend kona camping ranch which is newly opened, you can have free kona coffee, free fruits and free pancakes! and feeling there is absolutely great.