PHPGGC is a library of PHP unserialize() payloads along with a tool to generate them, from command line or programmatically.
You can download it from the following link: https://packetstormsecurity.com/files/download/152363/phpggc-master.zip
Source: https://packetstormsecurity.com/files/152363/PHPGGC-unserialize-Payload-Tool.html