The pet rock is a miscellaneous quest item in Fallout 76, introduced in the Wild Appalachia update. A medium-sized rock with a white smiley face drawn on it. It can be found in Camp Adams, northwest of the campfire, during the Ronnie McAdams version of Campfire Tales.
Fallout 76 random encounters, Fallout Wiki
Double dog collar, Fallout Wiki, Fandom
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Pet Peeve (Wastelanders), Fallout Wiki
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Pet rock, Fallout Wiki
How to Care for Your Pet Rock (with Pictures) - wikiHow
Pet rock, Fallout Wiki