Religious displays are not permitted in public schools. Courts have continually held that school districts may not display religious messages in public schools, including crosses, the Ten Commandments, bible verses, bibles, religious figures, portraits of Jesus, etc. even if privately paid for.
Cherry Valley Elementary principal Nancy Wortmann & Superintendent Erin Kane have been contacted by the local Freedom from Religion Foundation.
Here is a link to the Top 10 School Violations.