This will help you further
<?php
$timestamp = time();
for ($i = 0 ; $i <=30 ; $i++) {
$dates[$i]= date('M j', $timestamp);
$timestamp -= 24 * 3600;
}
print_r($dates);
Array
(
[0] => Feb 1
[1] => Jan 31
[2] => Jan 30
[3] => Jan 29
[4] => Jan 28
[5] => Jan 27
[6] => Jan 26
[7] => Jan 25
[8] => Jan 24
[9] => Jan 23
[10] => Jan 22
[11] => Jan 21
[12] => Jan 20
[13] => Jan 19
[14] => Jan 18
[15] => Jan 17
[16] => Jan 16
[17] => Jan 15
[18] => Jan 14
[19] => Jan 13
[20] => Jan 12
[21] => Jan 11
[22] => Jan 10
[23] => Jan 9
[24] => Jan 8
[25] => Jan 7
[26] => Jan 6
[27] => Jan 5
[28] => Jan 4
[29] => Jan 3
[30] => Jan 2
)