Snow Globes are small collectibles that can be sold to Jane in the Lucky 38 for 2000 caps each.
The Goodsprings Snow Globe is in the Goodsprings Cemetery up the road from Goodsprings. It is sat at the base of the back-left grave.
The Hoover Dam snow globe is sitting on the welcome desk inside the Hoover Dam Visitor Center.
The Snow Globe is found on the counter just inside the lodge.
Lucky 38 Casino
You first need access to the Presidential Suite. It is in the cocktail lounge, behind the middle cash register next to a green lamp.
Nellis Air Force Base
Inside the Boomer Museum. On the table to the right, just after entering.
Old Mormon Fort
As you enter, go all the way to the right, where there is a door to the tower. The Snow Globe is upstairs on a shelf.
Vault 21 is the Vault in The Strip. It is in an Average locked room in the northeast corner.
This Snow Globe is only accessible with the Dead Money DLC. Enter Salida del Sol from the southern-most entrance. You can see the entrance to the Dean's Secret Stash if you go down the stairs if you look up. To get to it, go up the east stairs and follow the rooftops back. You will get 2000 Sierra Madre chips when you pick it up, and it will be teleported to where the others are.