The first one is called "Moonpenny Island" by Tricia Springstubb. It's about two girls, Flor and Sylvie, who have been best friends since they were little. They live on a small island where Flor's dad is the lone police officer and Sylvie's dad is the mayor. Big changes start when Sylvie is sent to a school on the mainland, then Flor's mom leaves to help take care of her grandmother. Flor's sister also seems to be changing. The characters in this one interesting and the story line is compelling. There are big themes of friendship and honesty and how do you best help people. It was nice.
The second one might have more boy appeal. It's called "The Friendship Riddle" by Megan Frazer Blakemore. It's also about two girls in 6th grade who used to be friends. Ruth has been abandoned by Charlotte and they live in a small town in Maine. One day, Ruth is at the library (Charlotte's dads house the library in the building that they own) and finds a riddle in a book that she's shelving. She asks Charlotte about the riddle and it turns out Charlotte found one too, but finds the riddles beneath her. So instead of pulling them together, it seems to be pushing them apart. But Ruth keeps looking and trying to solve the riddles and she moves from having a solitary quest to have a group of friends that are willing to help her and who also want to join the quest. It has text references to the Hobbit, which might draw in some boys (who are willing to go past the part where Ruth has to go shopping for a bra). The riddle part might also be a draw, much like the riddles in "The Book Scavengers" by Jennfier Chambliss Bertram.
This last one "Adventures with Waffles" by Maria Parr is a bit of a twist on the friendship theme. In this one, Trille is a boy, who is worried Lena is not his best friend. He definitely considers Lena his best friend but she never tells him that he is her best friend. Lena is not an easy person to be friends with. Lena has many great ideas. One of her great ideas is that, after hearing the story of Noah in Sunday school, that THEY should try to put two of every animal into a boat. They think they don't have time to build their own boat, so they use Trille's uncle's boat. Things are going well (dogs, cat, ok only one cat, but it was a very fat cat so it counted as two, worms) until they decide to go and get one of the cows. There are parts of this that are laugh out loud funny and also parts that are sad. It's translated from Norwegian and there are parts that are very culturally specific (the expression that Lena uses for surprise or dismay is "Smoked Haddock!", which I wish I knew why THAT was an expression). It would connect well with stories about Ramona, Junie B. Jones, or Clementine.