For some reason this is only returning the description of a single item in the HashSet even when there are several items. I am not sure if the (Item)iter.next() is only getting the description of the first item in the list and that is why.

    /**
     * 
     */
    public String getMyItemsDescription()
    {
        String returnString = "The items in your inventory are:";
        for(Iterator iter = myItems.iterator(); iter.hasNext();){
            returnString = " " + ((Item)iter.next()).getDescription();
        }
        return returnString;
    }

returnString = " " + ((Item)iter.next()).getDescription();
discards any orevious data in returnString.
How about
returnString = returnString + " " + ((Item)iter.next()).getDescription();
top keep the existing values