Those fungi may be growing on a the dead roots of another that had been removed years ago. I wouldn't panic too quickly about your present tree. I had some growing and I didn't realize there had ever been a tree there.
Glad to hear you had an uneventful trip home.
Sounds like our Indian Summer is over and much cooler wet weather is forecast. At least it was nice while you were here.
I picked up 6 more pails of walnuts and got them all shucked before the rain began. I am done for this year.