SOLUTION:
The clue "A Lesson Left Behind" points to the old Tibbee Schoolhouse. The first-person narrative strongly evokes the atmosphere and experiences of a rural, one-room, schoolhouse from a past era, with its students from "farms and fields," a dedicated teacher, and characteristic details like the school bell and creaking floorboards. The location in Clay County and key descriptive phrases such as the teacher living "just beyond the track," the sound of "trains," and the trouble crossing a "flooded creek" directly allude to the Tibbee Schoolhouse's location near both a railroad line and Tibbee Creek. The poem captures the common fate of such schools eventually falling into disuse ("One day, we didn’t come back"), leaving behind an enduring "lesson" in history.