From episode 1x07 "The Heart is a Lonely Hunter".
From episode #216 "Peter".
From episode #317 "Stowaway".
Mulder finds Guy Mann at the cemetery and gets the whole story out of him in episode 10x03 "Mulder & Scully Meet the Were-Monster".
Laurel mourns over her sister's grave with her dad in episode 1x16 "Legendary".
Source: 50shadesjournal — Twitter