Weird fungus? Stuff please help identify

This weird looking (I feel fungus) stuff has come Out in my new garden beds and I want to make sure it’s safe because I transplanted my blueberry bush into this garden. There are two pictures one is a day old (orange/brown) and one is a week old (dark brown). In the bed is Bunnings composite and potting mix and sugarcane mulch and final layer cardboard. Some Of the pine logs are brand new some have been reused from other sections of ym garden. I’ve never had this before. I’m an hour north of Sydney nsw