The Winchesters attend a sermon at Lori Sorenson's father's church in episode 1x07 "Hook Man".
Source: Supernatural Locations
The Legends attend a wedding and are surprised when the bride declares her love for her maid and all maner of love hijinks ensue in episode 4x11 "Séance and Sensibility".
The whole town attends the funeral for Andrew Eggers and afterwards Officer Wentworth ends up telling the boy's father about the profile Scully came up with in episode 11x08 "Familiar".
From episode 1x07 "St. Luke's".
From episode 1x10 "Fallen Angel".