Dr. Seuss’s Green Eggs & Ham and Other Stories, Emerald City Theatre Company, at the Old Town School of Folk Music Children’s Center. Emerald City proves once again that it’s one of Chicago’s best children’s-theater troupes with this musical celebration of all things Seuss. Under the expert direction of Nancy Howland Walker, this imaginative staging opens with songs based on some of Dr. Seuss’s best-loved works: Yertle the Turtle is interpreted as a rollicking gospel number, and Green Eggs & Ham takes the form of a Busby Berkeley-style musical extravaganza. Calling themselves the Whats of Whatsburgh–lovable thespians who can’t resist a captive audience–the five ensemble members keep the energy high throughout the show’s scripted first half with a kid-friendly blend of slapstick and vaudeville humor.