For reasons unknown to me fresh yellow corn has disappeared from most supermarket produce departments over the last few years.
OTOH the small kernel, (too) sweet white corn is everywhere at this time of year.
I know yellow corn is still around in the freezer section (frozen kernels and mini-cobs) and at farmers markets (if you are lucky). A month ago at an FM I talked to someone from a well known growing area (Brentwood, CA) who was surprised at my comment.
Mike in SoCal