The speaker remembers a girl from their old town who scattered seeds wherever she went, while the boys carved their names into wet cement. The boys mocked her, saying she'd never leave a mark if all she left behind was leaves and bark.
Years later, the speaker wonders about those boys and imagines showing them what happened. The streets where they played are now buried under green, and an endless forest stands where their names were scratched. Their marks, meant to last forever, are gone, while the girl's quiet work grew into something huge.
The mood is gently triumphant, with a little wry satisfaction in it. The speaker clearly admires the girl and wishes the boys could see their mistake. The closing lines state the message plainly: the loudest people aren't always the ones worth hearing, and the people who change the world are often the ones you least expect.