Eric Carle books (hungry caterpillar etc) are great.

DS loves the "that's not my..." series, they're touchy-feely books with descriptive words. We have the lion, the dragon, the bunny and the penguin ones so far, every time I get a book for me I let DS pick a book too!

"This little baby" is another great one, DS loves the baby faces and the mirror ending - the most kissed mirror in the world!

I have a few baby bibles and baby bible stories that DS enjoys - including ones with flaps, ones with prayers in, bright pictures, pastel pictures... DS likes those too.