In just three short lines, a speaker wakes into a gray, blurry morning and finds themselves alone with a cold pie. That's the whole scene, and its smallness is the point. The title, "Solace," sets up an expectation of real consolation, but what arrives is a leftover pie, and a chilly one at that.
The humor is dry. A cold pie isn't much of a companion, and the poem seems to know it. Still, the speaker doesn't sound desperate. The word "find" in "I find myself alone" suggests a quiet surprise, as if the loneliness simply showed up with the fog. The fog itself blurs everything outside, leaving the speaker and the pie as the only clear things in view.
The mood is wry, gentle, and a little melancholy. It can be read as sad, since the comfort is so slight, or as warm, since any comfort is something. The poem leaves that balance for the reader to decide.