You eat them! They're a tasty treat that comes with your Rift, as a thank you for being a great customer. /s
I'm sure they just include them to help keep the Rift dry during shipping, personally I'd just keep them in there in case your room is ever really humid, or if you take your Rift on a road trip and are worried about moisture for any reason.
Personally I'd say the best place is in the compartment the Rift actually sits in though, but I doubt it matters really. 🙂
