Q: What words have folk etymologies (e,g., "an apple" from "a napple")?
A: This phenomenon is also called "metanalysis" or "affix-clipping."
adder (a nadder -> an adder) aitch-bone (a nache-bone -> an aitch-bone) apple (a napple -> an apple) apron (a naprun -> an apron) auger (a nauger -> an auger) eyas (a neyas -> an eyas) newt (an ewt -> a newt) nickname (an eke-name -> a nickname)