If you're comparing the two, why not take a look at this photo (attached).
Consider what was going on during the time of the Great Depression. You have the Dust Bowl happening in the west (which you can link very easily to the first paragraph of the text. Think about looking at the visual imagery the author describes).
The author speaks a lot of the nostalgia, which again relates to the history. Right before the Great Depression, people were living this life of luxury in the Roaring 20s. Consider the look in the woman's face. How does the nostalgia read in her eyes, her body language, and so on. You can connect this feeling of nostalgia with the quote about the marigolds reflecting "the strangest times." Consider how the speaker portrays this feeling of nostalgia or the memory of what once had been.
The marigolds represent not only the past but also... what could have been. Consider how you can link the hope that can be evident as well in the woman's eyes.
One reason is that it shows that it is a part of the rhyme scheme and the other reason is that it highlights the significance of light. Hope this helps!
If someone entrusts you to write a speech for a wedding, it's more meaningful to write it yourself. Take inspiration but don't copy word for word. That takes the sentimentality away.
