If you like "Big Stone Gap" by Adriana Trigiani
Since you liked the diverse characters in Adriana Trigiana's Big Stone Gap Series, you may enjoy reading some of the following books:
Bailey White has not written a trilogy; however, her titles "Mama
Makes Up Her Mind and Other Dangers of Southern Living," "Sleeping at the Starlight Motel and Other Adventures on the Way Back Home," and "Quite A Year for Plums" introduce colorful, offbeat Southern characters.
Virginia-born Lee Smith has several titles that may interest you:
"Black Mountain Breakdown," "Oral History," "Family Linen," "Saving Grace," and "The Last Girls." Her books definitely depict the life of women from the Appalachian region.
Another Southern writer is Kaye Gibbons. Three titles you may want to consider are "Ellen Foster," "Virtuous Woman," and "Cure for Dreams."
An author who is mentioned as being similar to Trigiani is Pamela Duncan. Titles by her include "Moon Women" and "Plant Life."
Since the authors that I have mentioned do not have trilogies as does
Trigiani, perhaps you might want to travel from the Appalachian area
to the Pacific Northwest and read the "Eclipse Bay" series by Jayne Anne Krentz.
I hope that these suggestions will help you find some good reads.
Jane Kosa, Reference Librarian