In 1983 I'm detecting at Cypress Jr. College, in Calif. Using my Whites 5900D2, with an extended shaft and hip mounted box I could really get that coil moving, which with that machine meant deeper finds.
Got a deep signal, and although there were people around the field, I started digging. Approaching 12" I finally got the target out (this was before they invented pinpointers), and became the proud owner of a 1902 Indian head penny.
Absolutely no idea why it was there...the college was built in 1966, and prior to that I believe it was cow pasture.