The first rock/pop concert was Linda Ronstadt at Blossom, 1975 with my brother.
Chicago with the Beach Boys opening, 1988 or 1989, Fiddler's Green
Molly Hatchet, somewhere, not my first choice!
If it counts: Peter, Paul and Mary played at a May 4th memorial when I was at Kent State, and I was there.
Fleetwood Mac, in May