Macro to go thru directory of Excel files

Looking for someway to go thru a directory (with or without sub folders) and for every Excel file it finds, open the file and Copy - Paste Special Values each worksheet in the workbook. I wouldn't know how many sheets any given workbook may have until it opened. Can this be done? Copy and paste part is easy enough but hoping not to have to have someone open each one and then run a copy paste macro for each sheet and workbook.