Not fears which have followed you into adulthood, but little things you remember being afraid of. I'll start:
My shoes walking away without me (I'd seen it in a cartoon).
Seeing a toilet with the seat up: it looked like a monster with a wide open mouth, and teeth (the rubber supports), and right at my eye level as well. Also, if I had to put it down myself, there was a danger that it might fall with a bang, before soft-close seats.
Sinking into mud, as if it was quicksand. My brother once lost a welly in some particularly sticky mud.
Alarm clocks, especially if they glowed in the dark, or had bells on top.