Something Sentimental

Something Sentimental is a side quest in the Fallout 76 update The Legendary Run.

Walkthrough
The quest starts by traveling to Foundation and speaking with Maggie. Alternatively, one can enter Monongah Mine during the A Colossal Problem event and pick up a holotape entitled A father's goodbye, which will also lead to her.

She tasks the player character with finding a way to enter the mine for the purpose of finding any trace of her father, Earle. She mentions that a large explosion may pry the mine's entrance open. Another clue as to how to gain entrance can be found in the form of a raider's note.

In any case, the next step is to personally drop a nuke on Monongah Mine, triggering the event quest A Colossal Problem, thus gaining access to the mine's interior. Progressing the event quest results in the player character finding and having to kill her father, who has mutated into a powerful wendigo colossus. Afterward, one can find his pocket watch on his remains.

Traveling back to Maggie will conclude the quest with different outcomes:
 * Telling her that nothing was found allows for keeping the pocket watch.
 * Telling her that only the watch was found results in losing the watch and gaining 60 caps as well as ~300 XP.
 * Telling her the truth about her father's mutation and death results in losing the watch and gaining 25 caps as well as experience.