One of the main factors that makes Mayella different from the rest of her family members is that while she understands her isolation, she wishes for more. The flowers are a symbol of Mayella’s desire to make her life even just a little bit better. It is this desire that sets off the whole chain of events that causes Tom Robinson’s trial
Mayella is a simple country girl. She has little education, and is no more than a glorified baby-sitter. The children only go to school for one day, and mostly fend for themselves. Mayella has no help.
Against the fence, in a line, were six chipped-enamel slop jars holding brilliant red geraniums…People said they were Mayella Ewell's. (ch 17)
The flowers allow us to see an interesting side to Mayella’s character. It would be easy to present her as only an ignorant liar. Instead, the flowers are a sign that she is trapped. Mayella is not happy. Tom Robison was a ray of sunlight in her life, until she got caught.
The fact that we are supposed to sympathize with Mayella comes from her having obviously been beaten by her father and possibly abused in other ways, and the juxtaposition of information about her life with Tom Robinson’s testimony.
As Tom Robinson gave his testimony, it came to me that Mayella Ewell must have been the loneliest person in the world. (ch 19)
Mayella is not a monster. She is a child trapped in an untenable situation. She got caught up in matters beyond her control. What she did was wrong, but the flowers add a multidimensionality to her character.
The relevant detail which contrasts with the disorder and deprivation of the rest of the Ewell property is, 'brilliant red geraniums, cared for..tenderly'. This shows that Mayella has an eye for beauty and the use of the word 'tenderly' shows she is capable of fine feeling.
It is linked in Scout's mind to her efforts to keep clean, 'Mayella looked as if she tried to keep clean, and I was reminded of the row of red geraniums in the Ewell yard'. These behaviours are linked because they are both attempts to rise above her shockingly squalid background.