I am not going to do this very often I hope, but I found a neat idea on another blog on how to store book units. This is going to be a short and sweet blot post as most of the information is in the blog post link that is featured below! I am going to direct you over to Fern Smith's Classroom Ideas!
Check it out her post here : Book Unit Organization Here is a picture from that blog to give you an idea about how she stores the book companions/book units!
You could store the book, the TpT items, flashcards and construction paper all in one area! That way when you go to grab "March Activities" you have it all together in one tub!