she tipped the contents out onto the carpet , besides his rather battered reading book , a couple of exercise books and a well decorated pencil case , there was an empty coke can , an apple core , a pair of laces for his trainers , his black plimsolls , one football sock , his school cap , an assortment of chocolate wrappers , his empty lunch box , a dirty pair of blue shorts , two conkers , a piece of string , a stone with a hole in it , various football stickers and a grubby , white envelope .