green chalkboard texture for school display backdrop. chalk traces erased with copy space for add text or graphic grunge

green background dark paper black abstract wall vintage grunge concrete texture stone wallpaper material rustic pattern structure watercolor floor old art cement design frame business grain bronze cardboard light banner textured surface retro template vignette poster backdrop decor ancient empty decoration digital effect blank paint modern curved urban color sand chalkboard school display chalk traces erased copy space add text graphic board education concepts