The amusement equipment is made of bronze and can be traced back to more than 2,000 years ago.
One of the artifacts, with a metal ring at one end, was found in the tomb of the Han dynasty on 2012 (206BC-
8AD) archaeological workers in Yizheng city, western Jiangsu province.
The second toy was found in the tomb of the first King Li Fei of Jiadu, and the base was flat.
It is believed that the use of these items is common among ancient Chinese royalty.
Fan Zhang, director of the exhibition hall, said: "The available bronze penis is still a relatively rare discovery, although far from unheard of, and occasionally found in elite graves . ".
"They are all made for use, and we can speculate on how they are worn based on their various foundations.
"They are all custom made, and those of us here may have been tied up with leather or silk thong, although it is not clear whether they were designed for men or women, Zhang added.
The "tomb treasure" exhibition is held at the Asian Art Museum in San Francisco, just 160-
Collections include decorations, offerings, and pots of silver and ceramic urns for bathing.