Mercy Watson

Kate DiCamillo long since conquered children’s publishing with a Newbery, Boston Horn Book Award, and as a National Book Award finalist. 

Two films based on her books didn’t hurt her reputation any

(though I thought the animated Tale of Desperaux ill-advised to jettison most of the original story).

But the books which most appeal to my family are her starter chapter picture books starring the “porcine wonder,” 

Mercy Watson (Theodore Geisel award). 

Mr. and Mrs. Watson as depicted by illustrator van Dusen 

are rather round and pink themselves, so perhaps their adoption of a pig as surrogate daughter should

not surprise us.

Mercy’s immense fondness for buttered toast and willingness to sleep tucked up in a child’s bed may puzzle adults, 

but children rarely worry about such trifles,

focusing instead on Mercy's attempts to drive a car 

and capture a thief (among other exploits).

Again, the series format allows kids a chance to get familiar with the characters,

who include not only the Watsons, but their neighbors, 

the elderly Lincoln sisters (Eugenia and Baby, who both embody and defy older women in kids' stories stereotypes),

and various bit players like Officer Tomallelo.
I've mentioned Mercy before, as a librarian pick, and
if you're interested in finding other good choices for elementary readers, you may want to visit that blog 
entry.