How Many Days Has What?

"Thirty days hath September" is still used to remind people how many days there are in each month. We really don't know where this came from, and I found a whole lot of variations, maybe two dozen, with no problem at all. The origins of the lyrics are obscure but use of Olde English can date this poem back to at least the 16th century. 'Fess up ... when was the last time that you found yourself muttering the words of the "Thirty days hath September" poem?

A medieval version is found in a 15th century manuscript, in the British Library:

Thirty days hath November,
April, June, and September:
Of twenty-eight is but one,
And all the remnant thirty-one

This one was definitely not found in the British Library:

Thirty days hath September,
All the rest I can't remember.
The calendar hangs on the wall;
Why bother me with this at all?

Anyway, November has thirty days and it’s November 30th.