This paperback (actually more of a pamphlet) was available in the 1960s. It contained several short stories. I believe it was blue and white. One of the stories involved a lost dog (I think it was a large black dog).
Another of the stories involved woodland creatures and lanterns in the woods. I believe there were characters named Happy & Hoppy.
The title is 1960s blue stories pamphlet
This may be one of the Haskin Booklets.
“Happy and Hoppy and Other Stories”—A collection of children’s stories and poems written especially for Haskin by Eva S. Phillips and colorfully illustrated by Richard Ehst. All about the delightful adventures of two little boys and their animal friends, this charming book is ideal for reading aloud. Every child will love smiling Happy and serious Hoppy! Large clear type …
The description comes from a 1958 children’s book catalogue ‘A Wonderful World for Children’ by Peter Cardozo.
Going to bookfinder.com, indicates two copies are currently available