This un-named woman is the mother of Penny and wife of Wyatt. She also has two other children, one boy and a second girl who we have never met. She lives with her husband outside of Omaha, Nebraska on their small farm where they raised their three children. Her name is not known.
She is the only mother of any members of the gang who has never been seen on the show, except Stuart Bloom's mother who is also only mentioned.
In "The Flaming Spittoon Acquisition", Sheldon implies that she's fat and Penny reveals that her mother smoked pot when she was pregnant with her.
In "The Status Quo Combustion" Penny calls her mother to tell her about her engagement to Leonard. She denies that she is pregnant and agrees that it is a first for their family.
In "The Transporter Malfunction", Leonard and Sheldon told Penny they didn't want to open the Star Trek Transporters she had just bought them because once you open the box, it loses its value. Penny relied, "Yeah, yeah, my mom gave me the same lecture about my virginity. I gotta tell you, it was a lot more fun when I took it out and played with it."
Penny talking to her mother.