If you're at a specific cell in a workbook, the current Find functionality (command-F) only allows you to search downward, to the NEXT cell that matches the value. I frequently need to search UP to find the PREVIOUS cell that matches that value, and there seems to be no such function. In a program as mature as Excel, this lack of basic functionality seems rather idiotic, and downright lame. I think you even used to have it, many years ago, and then got rid of it in a flash of lunacy. A simple checkbox in the search dialogue box that reads "Search Upwards" is all it would take...
William Clark commented
On Windows (I don't know about Mac.):
This could be like the "Direction" option ("Up" or "Down") in Notepad, with Radio Button Selection or keyboard shortcut Alt+U or Alt+D, and default to Down, so that it is consistent between programs. Maybe this should be an industry standard, if it isn't already.
Andrew Duncan commented
There is a Find Previous (shift command G) in version 15.21.1