I used actual dead leaves and put them through a blender to get forest floor ground cover. It's a good idea to bake natural materials like that at 80 degrees plus (Celsius) for about half an hour, to kill off any little mites or other microorganisms that might be living in them.
(https://1.bp.blogspot.com/-sRWOlw9HMAA/X7cXp7yWB0I/AAAAAAAAWh8/3TF2ZGbG2hcSYMX9nzQ3HuKHT_JNHLrfgCLcBGAsYHQ/s906/2020-11-20-SchlossbauerTrapdoorSpider.jpg)