On May 22, 2010 Laszlo Hanyecz paid Jeremy Sturdivant 10,000 bitcoins for 2 Papa John's pizzas which were delivered to Hanyecz's home.
This exchange is considered historic because it's viewed as the first use of bitcoin in a commercial transaction with bitcoin as the medium of exchange.
At today's BTC price, that would be $340,000,000 for 2 large pizzas... but back then it was only $41!