Rhiannon Lawrence is Topanga's mom and the (ex-)wife of Jedidiah Lawrence. She loves her daughter, and also seems fond of Cory, for whom she made many peanut butter and jelly sandwiches as a child. She allowed Topanga to stay in Philadelphia when she and Jedidiah moved to Pittsburgh because she didn't want to take Topanga out of high school in her senior year. However, she also attempted to take the oppurtunity to resolve issues with her husband, which she didn't reveal until State of the Unions.
Rhiannon first appears when the Lawrences meets the Matthews to plan Cory and Topanga's wedding. She and Jedidiah do not get along very well, and they announce that they intend to divorce. She hopes that their decision does not effect Cory and Topanga's relationship.
Cory, devastated by the loss of Topanga (who had left him because her faith in love was shaken by her parents' divorce), confronts Rhiannon in Pittsburgh to persuade her to see her husband. He does not understand the situation, and is pleased when she says she'll try to forgive him. What he's missing is that Jedidiah had left Rhiannon for another woman, Marie.
Rhiannon came to Pennbrook to tell Topanga the truth about the divorce, and she told Topanga that every relationship stands on its own, and she was pleased with her marriage despite it's outcome. This convinced Topanga to reunite with Cory. Rhiannon was also present at her daughter's wedding.
- Topanga refers to Rhiannon as 'Chloe' in the episode Cory's Alternative Friends. This is considered a continuity error.