Yardsailing is usually done by people who buy random things for a cheap price and sell on eBay for way more than what it's worth.
Yardsailing is also practiced by people who enjoy going to yard sales for the fun of it.
A person who goes yardsailing is known as a yardsailor. Yardsailors typically wake up early, search newspaper adds, and stay out till every last yard sale has been sailed.
Yardsailors are not to be confused with passerby's who stop at a yard sale just to have a look.
"WAKE UP! WE'RE GOING YARDSAILING!"
"Who knew this crappy chair I got for 2 bucks would sell for 40 dollars on eBay! I'm glad I went yardsailing!"