The Winchesters attend a sermon at Lori Sorenson's father's church in episode 1x07 "Hook Man".
Source: Supernatural Locations
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".