Originally "pease" like in the nursery rhyme "Pease Porridge hot, Pease porridge cold, pease porridge in the pot nine days old", this word was often mistaken as the plural form. By the 17th Century, people started dropping the "se" and calling the vegetable a pea.
Cherry was originally "cherise" from the old French ("cerise" in modern day). People thought it was the plural form and changed it to cherry.
Napron was misheard as apron so many times that by the 17th Century it became apron.
Umpire came from the Middle French "nonper" or without peer. People didn't always hear the initial n. It evolved into nomper, then omper and now umpire.
Originally this word was ewt, but if said with the article an it sounds like newt.
Originally this word was ekename which means added name. If said with an it sounds like nekename or nickname.
This word came from the Spanish "El largato" which was corrupted into "largatos" and eventually alligator.