Without seeing a picture of the knife and it's marks, a positive identification is not possible. Your description resembles a 877 or 876RB. If that is the knife, it is referred to as the "Shadow Lobster" pattern, and has either true mother of pearl or "marine pearl plastic" handles, depending on when it was produced. The Schrade Walden stamping was used circa 1947-1973, so your knife falls somewhere in that timeframe.
Value? Sorry, I generally don't do values. I might give ten and shipping for one if I really wanted one. Someone who collects that pattern might give more if it is in near new condition and comes complete with the original box, and if it is an earlier MOP and not a later MP handle.
Codger