Little House on the Prairie

Author:  Laura Ingalls Wilder
Lexile measure: 760
Language:  Acceptable, no potty language or swearing
Violence:  This story is best understood in the context of the conflict between white settlers and Native Americans.  There is a mention of "massacre", though younger readers do not need to understand exactly what that means to understand that the white settlers were afraid of the Indians.  Also, Pa regularly carries a gun.
Big Kid Mature Topics:  Jack, the dog, nearly drowns.  Ma is injured by a falling log.   Racism is also addressed in a fairly simple manner.
Illustrations:  Black and white drawings, every few pages
Plot:  moderately complex

Just be prepared that your child may play like a nice ladylike pioneer girl, or may run around screaming and playing "gun" after reading this book.   We had some serious discussions about some of the big kid topics in this book.  I'm not sure how much sank in.  But anyway, ours copy is falling apart--actually in complete disrepair-- and the others in the series are not much farther behind.  The writing is really superb and the topics that might be of issue are not gratuitous, they are part of the real threats people faced settling the West, and are covered in a way that elementary school kids (but maybe not 3 year olds) can appreciate without being overwhelmed by them.

Once you get to Silver Lake, there are also passages about some pretty heavy adult topics. also the reading level advances to an adult level.  So, if you get the complete set, you might consider locking up some of the later books until your child is at least a teen.