its almost a daily occurence..
I used to have a cat door into the basement, until I had to find the dead animal smell every day, so I closed that door.
We have a doggy door and its closed when were not at home or at night (cause she has brought dead birds and other stuff in) but during the day she will bring crap like that in..
last summer there was a full grown rabit, minus the head, that took me a while to find the basement, it was... really.. really disgusting
but we dont have a mole problem in our yard...