We're not there to see and interrogate your catalog.
Alternatively, open a technical support chat with Adobe who can remote into your system, 'seeing' things we cannot from just a description.
I agree, that tech support from Adobe may be the best way to get to the bottom of this.
There have been several posts, and I appreciate the help being offered by all who responded.
First, there are no other image files in my Pictures folder other than 4 that are in a subfolder called .picasaoriginals. I've drilled down into the subfolders and I've also opened a command window and with the DIR command and /S switch have searched the entire directory structure for image files. Note that the 4 image files in .picasaoriginals are not showing in LrC because I've not imported from that folder. You can verify that in the LrC screenshot below because the right pointing arrow/triangle to left of Pictures is grayed out indicating that subfolders have not been imported. However, even with the 4 in .picasaoriginals, there are only 7 image files in the entire folder structure, leaving 155 "ghost" images.
In answer to the suggestion from MikeRoetex that I look at one of the ghost images, I cannot do that because LrC is only showing me the three that actually exist.
But I did have some suspicions that there is confusion either in Lightroom or in Windows because "Pictures" is both a folder and a library. This is consistent with the response from Jack13088, whose advice is to just avoid Pictures (and presumably also Documents). I'm beginning to think that's pretty good advice.
A little background information is in order for those who are not overly familiar with Windows libraries vs folders. Many think they are the same thing, probably because at the surface at least, they are indistinguishable. Both can be opened in Explorer windows and in that sense libraries appear to behave just like folders, but they are more. Adding to the confusion. there is both a Pictures library and there is (or actually are) "Pictures" folders. The latter reside in the C:\Users folder structure, one for each user.
The libraries, and there are typically six, are Desktop, Documents, Downloads, Music, Pictures, and Videos. (Note that two of them - Desktop and Downloads - behave differently and might not strictly be considered to be libraries.) By default, each of these libraries is linked to a folder of the same name within the C:\Users folders. This default arrangement is one of the reasons that many think that a library and a folder are the same. But they are not, because a library can actually be linked to multiple folders, not just to the default folder of the same name.
Look at the third screenshot below. This shows the properties of my "Pictures" as a library, not as a folder. The properties of the Pictures folder are completely different. Rather than try to explain this further, here is a link to a very good discussion of all of this: https://www.windowscentral.com/how-use-libraries-windows-10
Coming back to the third screenshot below, note that my Pictures library links to 4 folders: Pictures (which is the folder in C:\Users), Downloads and two OneDrive folders that are also within the C:\Users folders.
I had a vague recollection that when OneDrive was installed it did some linking of its folders to the libraries, but until this issue arose had completely forgotten that. However, I have no idea why Downloads is linked into the Pictures library.
Nonetheless, this does not explain the 155 "ghost" images. In fact, the linked OneDrive folders contain many more images than 155.
Also, when importing from LrC, LrC does not show you the libraries. It only shows folders, and you have to drill down through C:\Users to import from Pictures, and the import will be from the Pictures folder and not from the Pictures library.
To test if there was confusion in LrC because the Pictures library is linked to far more folders that just the Pictures folder, I decided to click the Restore Defaults button and force the Pictures library to link only to the Pictures folder. I then removed Pictures from LrC. Quit and restarted LrC. Imported from C:\Users\...\Pictures. It showed me three images would be imported, but after the import the count was back up to the incorrect value 162.
So, eliminating potential confusion between Pictures as a folder and Pictures as a library did not fix the problem.
My next step is Adobe support.