J.B.
For the 3 year old -"How I Became a Pirate," the Skippy Jon Jones series and ALL of the Dr. Seuss books. Get a book of classic fairy tales with great illustrations. My boys have LOVED that -Jack and the Beanstalk, Puss in Boots, Rumplestiltskin, Hansel and Gretel, Three Little Pigs, Little Red Riding Hood, etc. Those stories are also part of our societal lexicon, so kids need to know what they're about. Others for the 3 (and the 5) year old: A Bad Case of Stripes, Where the Wild Things Are, abbreviated Alice in Wonderland -although the 5 year old is probably ready to head into the real deal, lots of Little Golden Books like The Pokey Little Puppy. Don't forget Mother Goose's nursery rhymes! Rhymes are big at our house. Peter Pan is also a big deal -books and movie.
They would all probably enjoy Robin Hood and Tales of Uncle Remus. Unfortunately many think Uncle Remus is racist when it's anything but. The tales are old African folk tales handed down from slaves. The Wren's Nest here in Atlanta is Joel Chandler Harris's old home, and they have storytelling and group visits all the time. The children LOVE the stories -primarily told by African-American storytellers. It's a great way to share history too, and they all have a good moral to them.
For the 10 year old -check out chapter books from Beverly Cleary. I LOVED those -Ramona and Beezus, Henry and Beezus -boy and girl characters and they're great! Also -get into mysteries -Hardy Boys and Nancy Drew, Boxcar Children, Encyclopedia Brown. Judy Blume has some great classics too -especially "Tales of a 4th Grade Nothing" and the sequels "Superfudge" and one other. At 10, you can probably get into some of the really great classics that are a bit longer like "Treasure Island," "Black Beauty," "The Chronicles of Narnia" series, "Island of the Blue Dolphins," "A Wrinkle in Time," "Swiss Family Robinson," "20,000 Leagues Under the Sea."
OH -and also for the 10 year old (can't believe I left these off -some of my faves as a kid) -"King of the Wind" and "Misty of Chincoteague." "Sounder" -be prepared with "Sounder" for you both to bawl your eyes out! My 3rd grade teacher read it to my class chapter by chapter and at the end every single kid, boys included, had their head on the desk crying! It's a phenomenal book though -and the last three I named along with some others are all Newbury Award winners. "Walk Two Moons" and "The Giver" are also great books.