This is where the fence ends and the park begins.

But, how about using cash to send mail, rather than a stamp? Could that work?

The letter was adressed from me (Philadelphia), to my girlfriend in NY. 39 Cents composed of one Quarter, one Dime and four Pennies were attached into the spot where a stamp would normally go. An additional 5 cents (nickel) was attached at the bottom right corner of the letter as a “tip” to the postal worker.

I think the outcome of this “experiment” may have been an error though… take a close look at the “after” photos of the envelope to see what I mean.