Random Gifts from the Universe?

Yesterday before I left for the gallery I found the following beauties in my mailbox:

Do wasps ever just like... lift their homes and move to new places or should I be concerned that somebody put that there? (Because I'm concerned that somebody put that there.)

Last year Nick and I found a small skull on the back porch. Perfectly in tact - even had all the teeth. If I find it I will take a picture to share with you. Finding the wasps next gives me the same feelings. This little item is slightly too bizarre to just be sitting where it currently sits. Somebody must have placed it there... but who?