Children's compilation of stories and poems

Looking for a compilation book of children's short stories and poems that I read back in 1983. The story that sticks with me today is a humorous tale about a salesman who tries to sell toothbrushes two aliens but gives up when he realizes the aliens have no teeth. As it turns out the aliens he tried to sell to were the elders and had lost their teeth but the rest of the planet was filled with younger aliens who all had a full set. I wish I could remember more stories from the book.