Mayfield was suspended earlier this month for violating NASCAR's strict substance abuse policy. He had tested positive for methamphetamines during a random drug test in May, but repeatedly denied he ever used the drug.
In her suit, filed Wednesday in Superior Court in Statesville, N.C., Lisa Mayfield said her stepson called her a "whore," accused her of shooting his father (his death was ruled a suicide) and accused NASCAR officials of paying her for her affidavit.
She wants compensatory and punitive damages in excess of $10,000 each and "for such other relief as the Court may deem just and proper."
She also said she saw him using meth.
Jeremy Mayfield was suspended a second time on July 1 and could miss the balance of the Sprint Cup season.