Here is a Boy's size 5 Suit Set from DOCKERS.

It is a 4 Piece Set including Pants, Vest, Shirt and Tie.

The Pocket Square is attached to the Vest Pocket.

It is made from 55% Cottonand 45% Polyester.

It originally retails for $50.

I have another one in the same size currently on eBay with a light blue shirt and Bow Tie.