With the following formula you can construct a month table, containing all days of the month.
Formula
=ARRAYFORMULA(
DATE(
YEAR(NOW()), // first
A1, // second
ROW( // third
INDIRECT("A1:A" & DAY(EOMONTH(DATE(YEAR(NOW()), A1, 1), 0)))
)
)
)
copy / past
=ARRAYFORMULA(DATE(YEAR(NOW()),A1,ROW(INDIRECT("A1:A" & DAY(EOMONTH(DATE(YEAR(NOW()), A1, 1), 0))))))
Screenshot

Explained
The DATE
formula is used to construct the date out of the three integers it needs. The first is the YEAR
, being calculated from the NOW
formula. The second argument is the month that you want to calculate the days from. The third argument must be a day number. Because we're using an ARRAYFORMULA
, this is fed by a ROW
range. The range of the rows, is dependent upon the amount of days per month. This number is calculated as follows:
DAY( // days
EOMONTH( // days till end of month in date notation
DATE(
YEAR(NOW()), // from year
A1, // from month
1 // from day
)
)
Example
I've created an example file for you: Days of Month