What doe Lennie do with the water that makes him proud of himself?

Lennie
dabbled his big paw in the water and wiggled his fingers so the water arose in little
splashes; rings widened across the pool to the other side and came back
again.

Lennie is proud of his
ability to create movement within the water. The ripples and small splashes impress him.
He tells George to look at what he did after the above narration in the book. This shows
the simplicity of his mind since this is such a regular task. It also demonstrates he
can be entertained very easily.