stumble upon

Verb

stumble upon (third-person singular simple present stumbles upon, present participle stumbling upon, simple past and past participle stumbled upon)

1. (figuratively) To discover or find something by accident.
   • Underneath a black cliff where the incoming tide smashed on the shingle, they stumbled upon the mail hood of Hrothgar's murdered vassal.1961, Norma Lorre Goodrich, “Beowulf”, in The Medieval Myths, New York: The New American Library, page 35
   • During the course of his looking into Abedin’s S.G.E. status, the senator stumbled upon an O.I.G. “criminal” inquiry, commenced in October 2013, about whether Abedin knowingly got paid for hours she did not work while she was on vacation and maternity leave.2016 January 31, “Is Huma Abedin Hillary Clinton’s Secret Weapon or Her Next Big Problem?”, in Vanity Fair, retrieved 21 Jan 2016
2. (figuratively) To meet somebody by chance.