What was the maiden name of "Leave It to Beaver" TV mom June Cleaver?

June Evelyn Bronson Cleaver is a principal character in the American television sitcom "Leave It to Beaver". June and her husband, Ward, are often invoked as the archetypal suburban parents of the 1950's. June's birthplace is mentioned in one episode as East St. Louis while Ward is teasing her about her upbringing and they are discussing how they met.

June is played by Barbara Billingsley in both the pilot, "It's a Small World" (which aired in April 1957 on Studio '57), and in the original television series. Billingsley also plays the character in the show's television reunion movie, "Still the Beaver" (1983), and the show's sequel series, "The New Leave It to Beaver" (1985—1989). In the sequel series, Wally and Beaver are both parents, and June is a widowed grandmother.

In one episode, June has a sister named Peggy and an infant niece. She also has a spinster aunt named Martha Bronson (Madge Kennedy), who appears in a few episodes during the course of the series' run. No other relatives of hers appear on the show. June credits Martha with raising her, which suggests that June may have been a motherless child.  It is implied that June had an affluent upper middle class upbringing which may in part account for June's fastidious and fashionable clothing tastes throughout the series. June mentions that she was taught a formal curtsy in the event that she married a diplomat and Aunt Martha frequently proudly refers to their common Bronson lineage.