In Seedfolks by Paul Fleischman, Curtis is a native resident of Cleveland, Ohio. Fleischman chose Cleveland because of the diverse immigrant population that lives there.
I wanted to focus on recent immigrants. This led me to choose Cleveland as a setting, a city famous for its foreign-born population in the past and now absorbing immigrants from new quarters of the globe. Famous as well for its harsh, white winters, Cleveland would be a place with a short summer, where sign of the green would be especially precious. (Afterward. 9)
The Cleveland accent is sometimes called a Great Lakes accent, but its official title is, Inland Northern English. Because of television, all accents are slipping into what is known as American common, especially in larger cities, but Cincinnati has some specific characteristics. It is different from other accents in that it has a slightly more nasal tone but not as strong as Chicago. Vowels are a bit more stressed: Mom is m-ah-wm, apple is aaaapple, dot is d-ah-wt, and dog is d-ah-wg. There is also a prominent diphthong on words like axe. Instead of saying the word like "A-k-s" a distinctive "y" sound is placed in the middle of the word: "Aaa-yuk-s." Words tend to get slurred together "take them" turns into "takeyum." There is also a pinching of certain words, so they are almost swallowed such as the word “hear.” It sounds like "he-yer" in the very back of the throat and said very quickly.
I have included a YouTube interview of Chef Michael Symon. Both he and the reporter are from Cincinnati. The reporter's accent is a bit more distinct. I would assume, because Symon is on television, he has adapted his accent to be more general. However, in both, you can hear the distinctive accent markers. Listen for the more nasal sound and the flattened "a" when the reporter says "dot.com" and the swallowing of the yer sound when she says "here." Listen for the flattened a sound when Symon talks about his "aunt."
In the novel The Seedfolks, 28-year-old Curtis tries his best to win back his old girlfriend, Lateesha. He plants tomatoes for her in hopes she will talk to him again, because he knows that tomatoes are her favorite food.
In response to your question, we can infer what Curtis's dialect is. The setting for the story is in Cleveland, Ohio, and Curtis is an African-American male. Therefore, we can assume Curtis has an American accent to start with, and based on his words choices throughout the novel, such as:
"...That was the point of the tomatoes. I was showing Lateesha that just cause I got muscles don't mean I'm some jungle beast." (9.6)
that Curtis has an African American Vernacular English dialect, which is commonly spoken by working-class African Americans.