I went Googling a while ago to find a way to identify the wallpaper I have loaded on Win10. I came across this, I've no idea where at this point, but I've found it helpful from time to time and thought I'd pass it along. I just typed the below into a text file, then created a shortcut to the text file in a good place. (If you can actually remember the string, well I'd be impressed.
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RightClick on the StartButton, select "Run", paste in the following:
shell:::{ED834ED6-4B5A-4bfe-8F11-A626DCB6A921} -Microsoft.Personalization\pageWallpaper