337V: Society that enjoys watercress sandwiches

I read this book in six grade in the mid-80s.  I think it was a fantasy type story.  This society had once been in contact with humans (or maybe just one human).  He may have come over the mountains on a hot air balloon.

They got a few things confused about humans.  For example, they had a painting of a tree and a diagram of a family tree (genealogy chart).  They called the genealogy chart a picture and the painting of the tree a family tree.  So everyone in this society had a very carefully tended “family tree” in their yard.  Unfortunately, I remember nothing about the actual plot.

337T: Girl Starves Herself Trying To Feed Dead Brother

I randomly remembered a book I read probably a few years ago now. I only remember a few oddly specific things.

For starters, this main girl had a brother and she would bring food out to their yard to him and that is just always where they met up. By a tree, I think. Then later we find out that the brother is actually dead and she has been imagining this all. And the food she was giving him in like these sandwich bags is her food and she wasn’t eating. So she sort of accidentally starved herself. And I think at a point near the end, the parents see all of the sandwich bags full of food out by the tree and sort of realize what has been going on.

That is all I can remember, I hope you can help!!

337R: Children’s European Story Collection

Hello! I am looking for a storybook collection that I had in the 1980’s.

This book had a number of stories in it that seemed European based. I believe the first story was of a little boy whose mother made him green dungarees with a plane on them that he loved. He accidentally tore them on a fence and was very sad until his mother patched it with a star instead of a plane.
Another story was from Denmark about a boy whose father was a fisherman. The pictures in this one were monochromatic (rust colored.) The picture was of the boy standing close to the sea and possible the famous mermaid statue.
Another story was of a mother hedgehog. I believe it had a picture of a hedgehog in an egg cup.
I believe the back cover of the book was blue.
This book was read to me every night and it was my favorite. I would be so happy to finally find it again!

337Q: Hearts and Flowers

I am looking for a 1920’s-30s romance, where the heroine earns her living being a professional letter writer, and she begins a correspondence with a young man (invalid/injured?) using the persona of an elderly motherly woman.  The only other detail that I can recall is she sent the young man some women’s hats and requested that he choose the one he liked for her.

337O: Children Stories About Science

I remember two stories, and I believe they may be from the same book.  One story is of some kids that get “hired” by a local scrap metal company to figure out how to crack open metal cannonballs.  They first try burying it in the snow, but find that the snow acts as an insulator, preventing the cannonball from getting cold enough to crack.  The kids then re-try by leaving the cannonball in the open (at least that’s what I remember), at which point the metal is cold enough to crack.
The other story also involves children, this time on a beach.  They collect up seawater, rig up a distilling system, and then boil the water to make steam.  The steam is collected up as drinkable water.
Thanks in advance!

337N: Earth History As Scenes In A Play

Children's illustrated science book about earth history, in which each age (formation of the solar system, age of dinosaurs, building Egypt's pyramids, etc.) is presented as a scene on stage in a play, with curtains to the sides. Last scene is at a typical house in the present day. Might have been printed in the 1930s or 1940s, was available in a grade-school library in the late 1970s.

337M: Girl Escapes Dystopian World Through Sewer To Find Mother

In the mid- 90s we had a college student come to my class for a project on the impact of sci-fi/fantasy novels on kids.  We had a selection of books to choose from, like “Girl with the Silver Eyes” and the Tripod trilogy.  There was one I started, but had to give back the next day as the project ended earlier for some reason.
I think the title had something to do with “moon” or had the word “moon” in it.  It started with a girl escaping a city through the sewer (I think she lived there with extended family?) to go find her mother.  I think it was kind-of in the dystopian genre.  The mom was presumed dead, or shunned from society in some way.