come upon in WordNet English dictionary

1. find unexpectedly
   "the archeologists chanced upon an old tomb"; "she struck a goldmine"; "The hikers finally struck the main path to the lake"
   fall upon  strike  come upon  light upon  chance upon  come across  chance on  happen upon  attain  discover 
   
2. take possession of
   "She entered upon the estate of her rich relatives"
   enter upon  come upon  luck into 
   

come upon in English Wiktionary