In his Foreword to this book, Louis Untermeyer says 'This is a book to grow on. It is also a book to grow with. In these pages are poems that will become favourites; you will never lose your taste for them. They will be part of you as long as you live'. This has been true for me - I was given a copy aged nine and it has been a source of constant pleasure in the almost forty years since. It's a meaty volume with the poems arranged under subjects such as 'Creatures of Every Kind' and 'Wide, Wonderful World'. Louis Untermeyer often gives a little description or some information about the poems and their writers, and the illustrations, by one of my favourite artists Joan Walsh Anglund, are so charming that the fact they are mostly monochrome does not matter.
The book was first published in America in 1959, so there are some poets that you may not have heard of, and no 'modern' stuff, but as a teacher of primary English I have had cause to constantly refer to this book for inspiration. It does not patronise children with poems in artificially jokey language, and some long poems that tell a story, such as Browning's 'The Pied Piper of Hamelin', are included in their entirety. I have read this poem to many classes of children over the years with great success - they do not need shortened or modernised versions such as you might find in more recent anthologies.
It also has limericks, epitaphs, funny stories such as (my favourite) 'George Who Played With a Dangerous Toy, and Suffered a Catastrophe of Considerable Dimensions' by Hilaire Belloc, and many classics by all the famous poets whose names we know, including the prolific Anon. Verses included go back as far as Aesop and the Bible. There is something for everyone here, all of them, as Untermeyer says 'meant to be enjoyed. Enjoyment is the essence'. Hear, hear. I recommend this book.