Negroes Plan School Mixing At HuntsvilleHUNTSVILLE. Ala. (UPI) -Three Negro children quietly preregistered for classes in “white elementary schools Tuesday, school board attorney Joe Payne reported today.Payne said there were no incidents as Sonnie Hereford and David Piggie, both first graders, and John Anthony Brewton, who will be in the second grade, pre-regis-tered with white children.Veronica Terrell Pearson is scheduled to be the first Negro student to attend Rison Junior High School next Tuesday but only new students in the system and first graders are required to preregister.Other schools to be integrated next Tuesday are the Fifth Ave-. nue elementary school, Terry Heights elementary and East Clinton elementary.The Huntsville school board was ordered two weeks ago to admit the four Negroes ot white schools and to present a plan for complete school integration in January.