This verse from GUEST,Karen, Cheshire, Uk 's post:

Mrs Cooper dressed in black
Silver buckles down her back
I love her she loves me
Lock the door and turn the key!


are almost exactly the same as the first two lines of the American children's rhyme:

Miss Mary Mack dressed in black
silver buckles up and down her back.

-snip-

Do those two lines show up in any other children's rhymes or English folk songs? If so, I'd appreciate someone posting which ones. Also, I read somewhere that those lines come from an English riddle "What is a coffin?" Is there any truth to that or is an example of that fakelore?