PLATTE, S.D. -- Platte pulled off a rally and a walk-off victory on Sunday night in Sunshine League amateur baseball play, winning 6-5 in 10 innings over Mount Vernon. Richard Sternberg drew a bases-loaded walk in the bottom of the 10th inning to win the game, as the Killer Tomatoes scored twice in the extra frame to pull out the victory. Joe Van Overschelde had an RBI double earlier in the inning to tie the game for Platte. Sternberg earned the…