i'm helping out a friend supply his child with some of the classics, by picking up copies of books like "The Strange case of Dr. Jeckyl & Mister Hyde" Treasure Island", "Huckleberry Finn" & "The Call of the wild" using my employee discount (25% off all donated items) at the local Goodwill
My daughters are 5 and 7, together we are reading the "Little House" series. We had a Pioneer Day here recently and it tied in very well. They have also made books for younger readers that uses the same verbage as the books, just uses a small section and more pics to make it less intimidating for young readers.
My 7yo just reads anything she finds at the library about animals, she just finished a Sea Turtle mini reference book so we made a bar graph of the different weights of the turtles (sneaking math in wherever I can). My 5yo is very excited to finally be able to find books at the library she can read without help. They are marked by grade level so she can read the 0.5-1.5ish range.