I don't think I understand your entire question.
I Do understand what you mean by patterns. It is a small 8x8 monochrome bitmap that you can create Which appears behind your normal background if you have one set. (Display Properties->Background Tab, and choose the "Pattern..." button)
The pattern you select is saved in the registry in HKEY_CURRENT_USER\Control Panel\Desktop in the Pattern value as a space delimited series of strings.
From what I can tell the actual patterns that you select in the dialog are hard coded into Explorer or a shell DLL, and not available for direct editing.
If you export the values in Desktop and import them to another PC, you will transfer the pattern, though.
Wallpaper itself iirc is merely a listing of applicable files from "C:\windows\web\wallpaper" unless you change the folder with tweakUI.