On your WordPress Dashboard do you want to have a notepad where you could make a list of items (perhaps a to-do list) or just some notes? If you are working on your site and you want something other than a paper notepad or a draft post or page to keep track of something or just have a few reminders. There is a plugin for that.

Here is the plugin called WP Dashboard Notepad discussed on the wpbeginner.com website. It is very simple. You can create as many notes as you want and you can drag and drop them anywhere on your Dashboard.

In the FAQ section of the listing of this plugin there is a few lines of code that shows you how to add colours. You could put these in the functions.php file of your child theme or you could put them in a custom site-specific plugin (which I have done here). Below is the code for the first two yellow colours. I added five of them. I got the colour codes from the Color Picker at w3schools.com.

/* WP Dashboard Notes
The following code adds colour options to the plugin WP Dashboard Notes.
*/
add_filter( 'wpdn_colors', 'wpdn_add_yellow1' );
function wpdn_add_yellow1( $colors ) {
    $colors['yellow1'] = '#ffffe5';
    return $colors;
}
add_filter( 'wpdn_colors', 'wpdn_add_yellow2' );
function wpdn_add_yellow2( $colors ) {
    $colors['yellow2'] = '#ffffcc';
    return $colors;
}