
That definitely sounds like
The Great Gilly Hopkins by Katherine Paterson.

Could it be
The Mysterious Benedict Society? There is definitely a special school and mazes in it. I don't remember much (if any) magic in it though.

Hillary, were these children's books, YA, or for adults?
Bahar wrote: "Could it be "The Root Cellar" by Janet Lund. The girl goes down into a root cellar and when she comes out she's in the past."A little off-topic, but I totally read that book! I was thinking about making a topic in this group for it, haha. Thanks :]

Heather, do you remember exactly when you read the book? And do you remember what time period the girl goes back to? Also, is it set in the USA, UK, or somewhere else? Any additional details would help a lot!

I only know of one, but there may be more!

Do you know about when your friend read this (very recently? decades ago?) and does she have an idea of when it was published? If not, that's ok, but it does help to narrow it down :]
Also, do you know if this was a picture book or a longer chapter book?
edit: I found a few possibilities
-
The Magic Wallpaper (I found some illustrations from it on
this website.
-
The boy and the lion on the wall-
Magical Walls

This probably isn't it as the details don't totally fit, but the part about killing birds reminds me of the book
Wringer by
Jerry Spinelli. Good luck finding for your book :]

That reminds me of the tv series Ghost Whisperer, haha. Unfortunately, I don't know what book that could be! Sounds interesting though.

Oh wow! Thank you guys! I've been looking for a link but didn't realize that I had to hover. Now I feel dumb, but I'm glad some nice people could help :'D

Ok, this feels like sort of a stupid question, but how do I find an old post of mine? A lot of forums have a button that lets you find what you've posted in the past, but I can't seem to find something like that on Goodreads (possibly I am not looking hard enough). I guess I can search for a specific post of mine, but there must be an easier way, right? Sometimes I posted in someone's topic and just want to check if they ever found their book or not.
Thanks for reading this and helping me out! :]
ETA: If you're reading this to find an old comment, just hover your mouse over your userpic! You'll find a link to your comments.

Could it possibly be a
Beverly Cleary book? I'm thinking one of
these books? It sort of sounds familiar to me.
I'm thinking
Jean and Johnny perhaps.

I know you said your mom doesn't remember a lot about it, but does she remember some more of the plot of the books? Or more character names?

You might want to check out
this Listopia list.

Amy, is there anything else you can remember about the book?

Just going to second that it sounds like The Great Good Thing! (on a similar Librarything group, this is a very commonly forgotten book :] )