In the city of Bordeaux, the Englishman Blessed Simon Stock, especially devoted to the Virgin Mary, Mother of God, and made glorious through brilliant miracles. – Carmelite Martyrology for May 161
Most images of St. Simon Stock show him receiving the Carmelite "scapular." This item comes in two versions. The first is a long, brown cloth of some width with a hole in the middle for one's head. This is worn by Carmelite Friars. The second, known as the Brown Scapular, can be worn by any lay person. Two small cloth squares are connected by brown cord or ribbon so that one square hangs on the chest and the other on the back. The Brown Scapular is thought to help the wearer escape the pains of Purgatory.2
The Acta Sanctorum's brief article on this saint (May vol. 3, 653-54) mentions a couple of miracles that could lend themselves to pictorial representation, though I have not yet seen any related images. In one, Simon objects as a vegetarian to being served a baked fish. When he throws the fish into the river, it swims away. In the other, when he runs out of Mass wine for his hermitage he renews his supply by blessing some water.
Prepared in 2015 by Richard Stracke, Emeritus Professor of English, Augusta University