A picture book I loved that I read recently was A Creature of Habit by Jennifer Smith, illustrated by Leo Espinosa. The Truth as Told by Mason Buttle by Leslie Connor and The Troubled Girls of Dragomir Academy by Anne Ursu are both wonderful middle grade books.
I also read The Truth as Told by Mason Buttle and I totally agree that it's a wonderful book. I have to add, too, that it was far better than the summary on its back cover makes it out to be. Here are some other middle grade novels that I recommend:
Ghost by Jason Reynolds (This book may be considered YA, but most kids who read this book do so in middle school.)
Ungifted by Gordon Korman
Belly Up by Stuart Gibbs (This is the first book in his FunJungle series)
The Secret Diary of Adrian Mole Aged 13 3/4 (This book is an oldie but a goodie. It might be considered YA.)
The Unteachables by Gordon Korman
Slacker by Gordon Korman (This book was published in 2016 but I think it's my favorite Gordon Korman novel.)
My middle schooler's favorite book is "The Miscalculations of Lightning Girl" written by Stacy McAnulty. She also liked Dusti Bowling's novel, "24 Hours in Nowhere." If you enjoy fantasy, my daughter also fell in love with Rick Riordan's Percy Jackson books.