Within the next week, please send old photos of kids in school plays and of office Christmas parties to Way Back When, Sun Magazine, 501 N. Calvert St., Baltimore, Md. 21278. You must include caption information and your daytime phone number. Also, enclose a self-addressed, stamped envelope if you'd like your photo returned. If your photo is your only copy, please send a good-quality duplicate, not the original. No faxes or newspaper clippings, please.