<?php
date_default_timezone_set('America/Los_Angeles');
$day = date("l");
echo date("Y-m-d", strtotime("last $day")) . "\n";
echo date("Y-m-d", strtotime("last $day + 1 day")) . "\n";
echo date("Y-m-d", strtotime("last $day + 6 day")) . "\n";
echo date("Y-m-d", strtotime("last $day + 7 day")) . "\n";