send something present to anytime in the past

[E-mantheseeker]

If you could send any item to anytime/anyplace/any person in the past what would you send?

Note: You can send something to see how it would affect the future, (a 2010 Ford car to a Ford factory in 1980) or something smaller in scale like giving yourself a PS3 while PS1's were new

 

[Lazy Kitty]

I really wouldn't know what to send, and I've been thinking about it for about 10 minutes now, the things I have thought of seem like a bad idea.