Our current pair have a habit of stealing toys from neighbours 
First we knew of it was when we found one of those fishing rod toys with a squeaky toy and feather having off it. Heaven knows how they got it though the cat flap 
We've had three "grump cat door handle" toys brought in, numerous cat nip mice, strings of mice, balls, toy soft spiders..,,
I've given up trying to return them (our neighbour, which is who they steal most of them from, is ok with that
)
We've also had a toy unicorn brought in from over the road where there are so my do you f girls. I did return that one - once I'd worked it out 
Cats have also brought in two fortunately dead rats. They've brought in live birds, including one memorable occasion when we came home to find them guarding the Christmas tree, where, on closer inspection, we found a baby magpie hiding 
Said cats: butter wouldn't melt in their mouth 