Cornfields seem to attract these things more than anywhere else, I've always found that interesting. Something about the geometry of the land maybe, or the electromagnetic properties of certain soil types - there's been some research into that.
What was the shape of it? Disc, triangle, or something less defined? And did you notice any effect on the local wildlife during or after - dogs, birds going quiet, that sort of thing. That detail gets overlooked a lot but it's often the most telling part of an encounter.
I had something similar years ago over moorland near Harrogate. Not a cornfield but the same sense of it just sitting there with total disregard for how objects are supposed to behave. That stillness is what stays with you isn't it. No noise, no movement, just presence.
Get your account written down properly before the details start to blur. Date, time, weather conditions, duration, direction it eventually went. You'll thank yourself later when people start asking questions.