Cecilia,
That loot looks to be for a 158 series machine.
The first part is a circle stitch which I don't have one.
The second part is a button holler. It will fit only Kenmores with the button holler drive under the slide plate. You remove the regular slide plate and instal that one. It actually has a mechanical drive in it to drive the button holler.
The third piece is a set of cams with their ID chart. I don't know which model those fit. They don't match any of my Kenmores.
The box of goodies does have some class 15 bobbins in it. Those will fit your 15 clone, but I don't know about the Elna. If the feet are low shank they'll also fit the clone.
The foot controller is specific to Kenmores and White made machines. If the wires are good don't cut 'em.
You have a few pieces there I'd be interested in.
Joe