A leather pouch full of sand, it was one of Dreams objects of office.
After Dream was captured by Roderick Burgess, his objects of office were taken from him and eventually were scattered. John Constantine told Dream that he found the pouch in San Francisco, where he bought it at a garage sale yeas ago, "I knew it was powerful but I never even managed to get the drawstring open...."
Dream insisted upon it's return, and Constantine took him to a storage unit where he believed the pouch had been for years. When he could not find it, a photo he did find, gave him a clue as to where it might be; an old girlfriend, Rachel, had stolen everything she could from him to convert it into drugs.
"Rachel was always playing with the pouch. Kept going on at me to try and open it. She'd ask me what was the point of having something magic if you don't use it?" (Preludes and Nocturnes: Dream a Little Dream of Me)
The pair find the pouch but it had destroyed Rachel, who had been all but consumed by dreams as she became addicted to the sand. Dream allowed her a peaceful death, and then he departed with the pouch.