$today = [datetime]::Today
$dates = @()
for($i = $today.AddDays(0).DayOfWeek.value__; $i -ge 0; $i--){
$dates += $today.AddDays(-$i)
}
$date = $dates | Out-GridView -PassThru
This snippet will return the days of the current week, and display the results using the Out-GridView for you to select the date you want.