Lots of good ones on here, hopefully this one can be enjoyed (creepily).
I had recently moved to a suburb just outside of New York City and I was about 4-5 years old. I had never really encountered anything funky (that I remember) but had my parents tell me occasional stories about me being sick with no pertinent causes when I was 2 years old.
My mother was a nurse and she worked an overnight shift back where we used to live in NYC, so she would take the one car that we had and it was a big to-do when she would get ready and leave for work after we ate dinner together.
So, we ate dinner, and I watched my mom get her bags and ask me for her customary kiss before she walked out the front door, into the driveway, and got into the car before driving to work.
My father and I would hang in the family room (or basement), I can't remember exactly in the evenings after dinner and he would watch TV while I played around with whatever kids my age played with.
That evening, I realized that I left something upstairs in my parents' bedroom. I cracked the door open with the light in the hallway on behind me to see someone in the bed - and I froze in my tracks.
There was something in my parents' bed.
It sounded like my mother, but it was too long ago to have remembered details. "Come give me a hug," the voice beckoned.
I was confused at first, because I distinctly remembered my mom walking out the door and getting into the car and driving away. "I thought you went to work just now," I said in reply.
"I felt sick and came back home," The voice beckoned again. "Now come give me a hug." I stood there for a second, and then shut the door, forgetting about my toy, and then walked back downstairs.
Recalling this only a year ago to my father, he was surprised to have heard this and asked me why I didn't say anything to him when it happened. I don't really know either.
I don't even really know what was in the bed and I'm sure as hell am glad I didn't try to find out.
TL;DR GHOST MOM