Update: I just ran across an old question (in the main English SE) regarding just this. For those facing the predicament of searching for stop words, the answers given there might offer some useful avenues to pursue: Can't search for a question about "that" and "which". The answers there are summarized below, for immediate reference.
One answer (from Jeff Atwood, two months after that post) suggested a Google search option; the details of the SE search interface have since changed (in that answer, the interface included edit fields that drew from several external search engines), and so the exact method used there no longer applies, but the approach itself is still an option for those readers who haven't seen it before (e.g.: entering {apples oranges site:english.stackexchange.com} into the Google search field).
Another answer (from Robert Cartaino, on the same day as the posted question) suggested the Related Questions option as being useful:
I find the "Related Questions" search extremely helpful for finding questions. Click on the Ask Question link and type in the title as clearly as you can remember it. The "Related Questions" will often do a much better job at finding the question than the native search tool.