What treasures do the old woman and her grandson find among the ruins of the church ?

From the text:

Our greatest excitement occurred when a fire gutted the large Chinese Presbyterian Church, three blocks from our house. Over the still-smoking ruins the next day, Grandmama and I rushed precariously over the blackened beams to pick out the stained glass that glittered in the sunlight. Small figure bent over, wrapped against the autumn cold in a dark blue quilted coat, happily gathering each piece like gold, she became my spiritual playmate:“There’s a good one! There!”