I don't think that "well-trodden path" warrants an entry, but "trodden path" doesn't, in my view.
OP: Kommt vor in Robert Frost, „The Road Not Taken“.
Actually it doesn't. "Trodden" only occurs in the lines,
And both that morning equally lay
In leaves no step had trodden black.
A comment on the poem: the central point is presumably expressed in the final lines,
I took the one less traveled by,
And that has made all the difference.
This being so, I find it strange, not to say unsatisfactory, that he says that the two paths have in fact had the same amount of "wear":
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same.