Toolbar options menu background color

To change the toolbar options menu color, add this to your toolbar element

app:popupTheme="@style/MyDarkToolbarStyle"

Then in your styles.xml define the popup menu style

<style name="MyDarkToolbarStyle" parent="ThemeOverlay.AppCompat.Light">    <item name="android:colorBackground">@color/mtrl_white_100</item>    <item name="android:textColor">@color/mtrl_light_blue_900</item></style>

Note that you need to use colorBackground not background. The latter would be applied to everything (the menu itself and each menu item), the former applies only to the popup menu.

Edit:

if you just want a white overflow popup menu just do this

<android.support.v7.widget.Toolbar    android:id="@+id/tool_bar"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:background="@color/ColorPrimary"    android:elevation="2dp"    app:theme="@style/MyDarkToolbarStyle"    app:popupTheme="@style/ThemeOverlay.AppCompat.Light"" />

and remove the redundant popupTheme your Style xml

<style name="MyDarkToolbarStyle" parent="Widget.AppCompat.Toolbar">     <item name="theme">@style/ThemeOverlay.AppCompat.Dark.ActionBar</item></style>

You should also include this in your top (parent) Layout

xmlns:app="http://schemas.android.com/apk/res-auto"

Simplest way

If you just want a white overflow popup menu just do this:

<android.support.v7.widget.Toolbar    android:id="@+id/tool_bar"    android:layout_width="match_parent"    android:layout_height="?attr/actionBarSize"    android:background="@color/ColorPrimary"    android:elevation="2dp"    app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"    app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

Also, take a look at the value of android:layout_height attribute.