Sorrow is my own yard (1)
Well, there you have it, folks. This widow is sad. Plus, her yard seems to be sad, too, based on this brief metaphor. So why then, is everything in bloom?
Thirty-five yearsI lived with my husband.The plum tree is white today (7-9)
What really stands out here is the jump from the mention of her life with her husband to the description of the plum tree. It seems like an awkward segue, but in a way, she's not really changing the subject, because her sadness has so thoroughly transformed her world that there's nothing that doesn't seem to reflect her loss, including the plum tree.
but the grief in my heartis stronger than they (15-16)
That about sums it up, doesn't it? No matter how bright, beautiful, and happy those flowers are, they won't help this widow shake her feelings of sorrow. And if these flowers won't help, we can't help but wonder if anything will.