The six Cobblestone magazines (Cobblestone, Dig, Calliope, Faces, Appleseeds, and Odyssey) have a stated policy of not responding to unused queries and not returning submissions, mostly because we usually receive queries, not complete stories or articles. However, the Dig and Calliope editor does often respond to submissions, but if you want your work returned, you'll probably need to specify that you do.
Marcia