Stanza 2 Summary

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

Who hath not seen thee oft amid thy store?

Keats returns to the personification of spring. He asks a rhetorical question: Who hasn't seen autumn hanging out by his or her (we're not sure yet) "store" of fruits, nuts, and other ripe things?
The word "store" suggests the abundance of crops, and you might think of a barn or a grain silo filled with the most recent harvest.

Sometimes whoever seeks abroad may find
Thee sitting careless on a granary floor,

Good, he's going to tell us how to find autumn now. It's like trying to find the leprechaun from the Lucky Charms commercial (we'll get those charms from you yet!).
All anyone has to do is travel through the countryside hitting up every "granary" – buildings where large amounts of harvested grain are kept cool and dry – until you find autumn sitting on the floor of one of them.
A silo is one kind of modern granary.
Now that the grain has been harvested, autumn doesn't have a care in the world. The work for this season is done and in the books.
We think "abroad" means "widely" or "through the countryside" or "across the land," rather than "in a foreign country."

Thy hair soft-lifted by the winnowing wind;

From this line we will tentatively guess that autumn is a woman. Not only because seasons were traditionally personified as female in European art, but also because this season has oh-so-soft hair. What kind of conditioner are you using, autumn?
We could play gender police and point out that Keats never uses "she" or "her" in this poem, but it's simpler if we use these pronouns while you just keep that fact in mind.
Autumn is like a college student when exams are over: she has nothing to do but hang out. She sits on the granary, and her hair is lifted by a gentle wind.
The word "winnowing" is perfect here because "to winnow" in farm-speak means to separate the grain (the edible part of the plant) from the chaff (its inedible covering). In centuries past, farmers winnowed their crops by having people beat the harvested plant with, say, large sticks. This action loosens the heavier grain, and then the chaff is light enough that it can be blown away, or "winnowed," in the wind.
The place where the grain and the chaff are separated is called the "threshing floor" – this is where autumn is hanging out.

Or on a half-reap'd furrow sound asleep,
Drowsed with the fume of poppies, while thy hook
Spares the next swath and all its twined flowers:

But, Keats, what if she's not on the threshing floor? Where do we find autumn?
Well, he says, she might also be on the furrow of a field that has only partially been harvested. She's taking a nap because, darn it, she's earned one. "Furrows" are the long, undulating hills that you see in fields, on top of which crops grow. The dips in the furrows are used for irrigation.
The speaker claims that autumn is basically drunk on the smell of the poppy flowers that she was going to harvest. She lies on the furrow while the "hook," or sickle, that she uses to cut the flowers lies unused. She hasn't gotten to the next "swatch" of flowers, so they're saved... for now.
The reference to poppies is no accident. Poppies were used to make opium, a drug that was popular in England in the 19th century. The writer Thomas de Quincey wrote an article called "Confessions of an Opium-Eater" about his experience with the drug, which was published the year after "To Autumn."
Of course, the smell of the flowers alone could not make someone intoxicated, except metaphorically.

And sometimes like a gleaner thou dost keep
Steady thy laden head across a brook;

The harvesting metaphors continue, as autumn is compared to a "gleaner," someone who picks out the last stalks of grain that were missed during the threshing process. Poor peasants would often be allowed to "glean" the field, the equivalent of picking up scraps after a feast.
Autumn puts her head down to cross over a brook, just as a gleaner bows his or her head to look for grains. Her head is "laden" or heavy – yet another image of weight.

Or by a cider-press, with patient look,
Thou watchest the last oozings, hours by hours.

But, if we still haven't had autumn, after searching all those other places, we might try the "cider-press," where she's totally mesmerized watching the fruit get squeezed into a thick, sugary juice.
Apple cider is the most common form, but pear cider is also drunk in England. Cider is frequently alcoholic, so this could be another reference to an intoxicant. See "Calling Card" for more on this trend in Keats's poetry.
Autumn is starting to sound like a real slacker. She has nothing to do, nowhere to be. She can "patiently" watch the thick juice or "ooze" of the apples drop from the press for hours on end.
"Oozings" is definitely our favorite word in this poem. It captures the concentrated sweetness of the season.