Return a list of weekdays, starting with given weekday

My task is to define a function weekdays(weekday) that returns a list of weekdays, starting with the given weekday. It should work like this:

>>> weekdays('Wednesday')
['Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday', 'Monday', 'Tuesday']

So far I've come up with this one:

def weekdays(weekday):
    days = ('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday',
            'Sunday')
    result = ""
    for day in days:
        if day == weekday:
            result += day
    return result

But this prints the input day only:

>>> weekdays("Sunday")
'Sunday'

What am I doing wrong?