Several years ago my partner Hal and I detected the yard of a 17th century farm in upstate New York. We found mostly modern clad and Indian head pennies in the yard, nothing really old and exciting.
Hal spotted an old barn with a field stone basement and foundation - the door was missing and part of a wall had fallen down in one area. This made it possible to detect parts of the dirt floor and to probe between the stones. After searching the floor and not finding anything Hal was ready to leave but decided to use his Tinytec to probe between the stones to see if some old farmer may have tucked a few coins in the wall.
Again, no luck, so Hal decided to give it up, but not before sweeping across
the top of the wall. When his probe gave a signal in one spot he thought it
was probably just a nail, but he reached up and felt a small can.
He grasped the object with his fingers and discovered it was an old tobacco can. As he brought it down, something inside the can rattled. In it were several coins including a valuable 1877 Indian Head cent. I don't remember exactly what the other coins were - they were nothing spectacular, but the 1877 was indeed a great find.