In addition to the books already mentioned, this should get you started:

By Eric Carle:
The Very Hungry Caterpillar
From Head to Toe
(already mentioned: Brown Bear, Brown Bear, What Do You See? series)

By Maurice Sendak:
Chicken Soup with Rice
Alligators All Around
One Was Johnny
Pierre

By Joy Cowley:
Dan the Flying Man
Dan Goes Home
Mrs. Wishy-Washy (There are a series of Mrs. Wishy-Washy books.)
The Meanies
The Birthday Cake
The Dancing Fly
Grandpa Grandpa
The Gotcha Box
(I can go on and on. She has so many great books for emergent readers. Joy Cowley is worth looking into.)

By Ezra Jack Keats:
The Snowy Day
Whistle for Willie
Peter's Chair

By Leo Lionni:
Swimmy
Inch by Inch
A Color of his Own

The Carrot Seed by Ruth Krauss
Seven Blind Mice by Ed Young
Are You My Mother? and Go Dog Go! by P.D. Eastman

All of these books possess language structures, patterns, and rhymes that are great for elementary ELL students, not to mention beautiful illustrations, most notably in books by Eric Carle, Maurice Sendak, Ezra Jack Keats, and Leo Lionni. And my students LOVED them!

I've read all of these books with kindergartner and first grade ELL students with success while tutoring for America Reads and completing my student teaching placement in elementary ESL in New York City public schools. There are definitely more that I can't think of right now, but I will add as I remember them/successfully use them in the classroom.