Leave the 'Display Name Search' field blank, unless you are looking for a post by a particular person (in that case you would type in their user name). Also, in the example you gave above, highlighting the main DD (English) entry and using 'egg' as a keyword rather than 'eggs' would give more results, if your initial search didn't turn up what you were looking for.
It's not a big deal, but this should have been posted in the
About this website forum.