I was in second grade in 1970 and my teacher read a book that I cannot find, but I don’t know the name.
All I have is that there were two main characters, maybe a young brother and sister, who travel to a faraway place, either a planet or a dream world, and they make friends with a little character named Jingles or Jangles. The little friend might be called Mr Jingles or Mr Jangles.
Wish I had more info to give.