Has anyone used those cash for gold mail in sites if so which ones are trustworthy?

I have not personally used any of the cash-for-gold mail-ins. They could be legit, but I am wary of sending valuable gold products through the mail to an unknown source. Honestly, I think your best bet would be to check with reputable companies. If you have gold coins or bullion, I'd consider reliable precious metals dealers like APMEX. If you have jewelry, I would take it to a local dealer you trust.