Do you have a Kenmore machine from the 70's?
These appear to be super high shank feet - only Kenmore machines used those, as far as I know. These particular pieces will fit a dozen or two machines from the early-mid '70's.
Top picture has what seem to be a zig-zag foot, a satin stitch foot and maybe a straight-stitch foot.
Second picture: buttonhole templates, a Q foot (for Qiana, a very popular polyester stretch fabric made in the 70's) and in the gold box, the fittings necessary for doing the chain-stitch.
Third picture: needle plate and template driver necessary for making buttonholes with the templates.
Fourth picture: seam ripper, spool felts and a class 15 bobbin.
If these accessories fit your machine, $20 isn't bad. You can get larger sets with hemmers and decorative stitch cams and such for the same or maybe a little more, but just these could increase your versatility way more than $20 worth.
