Book about a Magic Old Couple. It was printed before 1974. An old magical man and wife help some children. The kids enter a gate to visit the old man and woman in their back garden. The lady pours them lemonade from a pitcher that is never empty and the ice cubes never melt. That’s all I have. It was read to us by our 1st or 3rd grade teacher in either 1971 or 1973 ish