I'm sure this is nothing…. but so rare for me to see it.
Last night between 8:30 and 9:00 over Northwest Iowa I looked up and saw a full size jet airliner flying so low that I could make out both wings and the individual contrails from each engine, which vanished just a few feet behind the plane as-normal. If a normal jet airliner is about 1/16-1/8" wide in the sky, this one was a good 1/4" wide. Over my position, it was taking a path roughly from Mason City, Iowa to Grand Island, Nebraska.
I'm guessing it was about 20,000 feet high…. thought to myself that's really low for a jet airplane. Haven't seen one flying that low for many years.