Like the hollow handles on knives, etc., sometimes these salad set handles didn't get struck with the maker's mark or were so lightly struck that they weren't readable - some time ago, to narrow it down, I made a list of which manufacturers used which plastic (styrene/melamine) fork & spoon ends. Feel sure they were obtained from an outside supplier, and Towle did use that style, as did Reed & Barton, International, and Wallace - your pic is a bit unclear on my monitor, but you might look at Reed & Barton's 1960 John Prip designed
Lark pattern...
That said, it may just be a no-name piece - similar salad sets, often sold with a large silver-trimmed bowl made of wood, plastic, glass, etc., and sometimes individual bowls too, were pretty standard fare at mid-20th century department, jewelry and catalog stores - save locating the wholesaler's catalog or matching it to an identical item with marks, suspect tracking down a manufacturer would be difficult. All sorts of pretty much generic pieces, like sterling topped salt & pepper shakers in various materials, little individual shakers, weighted shakers, candlesticks, compotes, etc., were also very common, as were sterling handled serving pieces like pie servers and cake knives, along with smoking and novelty items - many often only marked 'Sterling'. Would guess that some were made by small jobbers and others by the larger manufacturers at lower price points and perhaps lower quality than their standard production too (also suspect some may have had long-gone labels/tags). I had a similar unmarked salad set for years, with ivory colored melamine (used to pair it with a big bright confetti Texas-ware bowl of the same era), the working end style was used by Gorham and to a lesser degree by International - very plain, never found a named line pattern, by any manufacturer, to match it.
~Cheryl