348N: Fern of the Forest?

I’m trying to find a picture book from the 90s about a girl who lives in a town where they only make dog houses. She runs away to the forest because she doesn’t want to make dog houses, and she builds an amazing tree house with the help of the forest animals. For some┬áreason I remember the title as “Fern of the Forest” but that might be completely wrong.

327J: Late 50’s/Early 60’s Long Island NY Grade School Reader

I’m looking for a book I remember so I can reconnect with the late sister I never knew.
I was born in 1965. I have one living sister (June, born: 1957) and one who passed away before I was born (Susan: born 1948).
I think the book belonged to my sister Susan, who was killed by a drunk driver in 1963. My parents couldn’t bear the pain so most of her things were not kept–too many memories. A few schoolbooks were left in the basement. I remember one especially…it could have been Susan’s or my other sister, June’s. I hope this information provides you with an idea of the time period/range of dates involved. Fairly positive it was before the mid-1960s.
The last time I saw it was a very long time ago, probably around 1973. I’ve been looking for it ever since. It was a grade school reader, blue boards…would have been used on Long Island, NY, in either Suffolk or Nassau County. I believe the first story was about boys vs. girls building a tree house. I think the girls put curtains, etc. on the windows. There are pictures throughout the book, but I don’t think the reading level was too young (not Dick and Jane, for example). There was also a story about a circus with an illustration I clearly remember of a lady in a tutu standing on the back of a running show pony.
I don’t remember much else. I think it was fairly thick, and the standard size for a hardback book.
Our address in New York was in St. James, NY, but my sister Susan only lived there for about two years. Prior to that I believe my family lived on Duffy Avenue, Hicksville, NY. This might help with the school districts.
If you could find the title for me, it would mean the world, because I could try to track down the book. When I was child I liked reading it, but I think when my mom saw it, it was either given or thrown away because it was too painful for my parents. Today the book would also be a connection to my late sister — even though it wouldn’t be her copy, it would still be something she read.
Many, many thanks. I’m sorry I can’t provide more information.