Lines 8-14 Summary

Get out the microscope, because we’re going through this poem line-by-line.

Or easy gold at the hand of fay or elf:

Lots of fairy and folk tales involve someone receiving gold in return for, well, pretty much nothing other than stumbling across a magical creature's stash (but there's usually a catch, right Rumpelstiltskin?). In other stories, people are rewarded for some reason or another. The point is that no one in those stories really had to work very hard to get those riches. Unfortunately, as is the case with so many people who have tons of money dumped in their lap, it goes just as swiftly as it came. The spoils of hard work, on the other hand, are even more valuable than the gold alone.
Looking at this line from the poetry angle again, the narrator may be addressing the tendency for artists of all types to talk about being inspired by muses and other lofty things. However, poetry can also be found in the everyday things. The poem inspired by this day cutting grass is just as valuable, if not more so, than the poem that was written after some zap of inspiration from a supposedly divine or otherworldly source.

Anything more than the truth would have seemed too weak
To the earnest love that laid the swale in rows,

The narrator is delivering only the pure, unadulterated truth of the situation. He feels that dressing up the situation with flowery language would somehow weaken the power of his poetry.
This line may be the most important in the entire poem—and that's saying a lot, considering the poem is so short.
Frost was often criticized for writing about the everyday moments and events in our lives because many critics felt that poems about things like mowing the lawn were too low-brow for hoity-toity poetry salons and readings. What he's trying to convey, though, is that poetry can be found anywhere, at any time, and by anyone. Frost said once in an interview that, "If poetry isn't understanding all, the whole world, then it isn't worth anything." These lines illustrate that.
Much like your grandfather telling you about his glory days working on the family farm, line 12 is like a tiny ode to hard work.

Not without feeble-pointed spikes of flowers
(Pale orchises), and scared a bright green snake.

Hard work is not without its beauty, rewards, or dangers.
Some people can make a dirty joke from any situation. When those people are also poetry critics, they can find sexiness even in a Frost poem about mowing the lawn. We have to admit that it is a bit strange that the most specific detail in this entire poem is the name of the flowers he is hacking down as he mows. It just so happens that these orchises derive their name from the Greek word "orkhis," which just happens to mean testicle.
The snake is easily associated with all naughty things, too. The problem is that there is little else in the poem to support that kind of snicker-inducing thought. Sometimes an orchis is just…an orchis.
What does seem likely is that Frost is talking about how life is complicated, full of both surprises and delights. It is only from the perspective of one who has experienced hard work that we can fully appreciate the complexity and beauty of life.

The fact is the sweetest dream that labor knows.

If anything is worth a funny face and a "wait, what?" reaction, it is this line. How can a fact be a dream when dreams aren't facts?
One thing that can help clear up the confusion about this line is to realize that this isn't the speaker speaking; it's the scythe. Or at least what the narrator believes the scythe probably whispered. The scythe isn't interested in fancy things or wild parties. It finds solace and beauty in the work it is doing, which is both a straightforward and undeniable fact.

My long scythe whispered and left the hay to make.

The scythe does its job—no more, no less. It does its job well and wisely, but it leaves the hay for the rake and the twine because that's their job.
The narrator has an admiration for such a simple-minded and dedicated farm tool. Day after day, it swings its pointy head through the grass, and it never complains. In fact, it has developed a singular wisdom about the world because of its simple existence.
And with that, both the speaker and the scythe call "cut."