What is the plot of "A Rose for Emily"?

I would answer this by saying that there isn't that much of a plot.  This story isn't driven by a sequence of events, really.  Instead, there are a series of vignettes that reveal Miss Emily's character and circumstances.

We see her run off the people who have come to ask her to pay taxes.

Then we are back thirty years and the horrible smell is coming from her house.  The men go to sprinkle lime and see her watching them.

Then we get about as much as there is of a plot -- this is the part where Homer Barron comes to town, has a relationship of some sort with Emily, and then leaves.

From there, we jump ahead, for the most part, to her funeral.

So, as you can see, there is not really a sequential plot like some stories have.