Mario Peshev

Delete all Custom Field entries assigned to posts that do not exist in the posts table.
Navigate to Settings -> Remove Unused CFs and delete all postmeta for non-existing posts.

DX Remove Unused Custom Fields

Does exactly what it says.
Installed, navigate to the settings page, click "Delete" and Done! Cannot be easier than that.
Thank you!



Simply Awesome!

Delete the Custom Fields from your postmeta table where assigned posts no longer exist.

webdeveric

This plugin provides a dashboard widget that lists recently edited content for quick access.
Options (per user settings):
<ul>
<li>Number of items to show</li>
<li>Excerpt length – number of words (0 = hide)</li>
<li>Show only your edits</li>
<li>What post types to show</li>
<li>What post statuses to show</li>
</ul>

Recently Edited Content Widget

This plugin provides a dashboard widget that lists recently edited content for quick access.

DX Remove Unused Custom Fields vs Recently Edited Content Widget