linewbie

WP Post Icon is a Free and Open Source WordPress plugin which is enable blog authors to upload and automatically insert topic icons or images in to your posts on the fly. You can control the position of the icon. Just select which image to display when you are writing a post, it will be automatically displayed.
<a href="http://www.linewbie.com/attach-diy/files/wp-post-icon.zip" rel="nofollow ugc">Download now!</a>
Features:
<ul>
<li>Automatically insert your topic icons in to your blog posts.</li>
<li>Very little manual work is required, just select which image to display when you are writing a new post.</li>
<li>
You could also use no image at all.
</li>
<li>
<a href="http://www.linewbie.com/sf-forum?forum=8&page=1" rel="nofollow ugc">Support</a>
</li>
<li><a href="http://www.linewbie.com/2008/02/wp-post-icon.html" rel="nofollow ugc">Version History</a></li>
<li><a href="https://wordpress.org/extend/plugins/wp-post-icon/faq/" rel="ugc">FAQ</a></li>
<li><a href="https://wordpress.org/extend/plugins/wp-post-icon/installation/" rel="ugc">Installation</a></li>
</ul>

WP Post Icon

Enables blogs authors to upload and select topic icons or images and have it automatically show up in their blog post.

Web Guy

Add a favicon.
Set the favicon URL under Appearance > Customize > Site Identity > Site Favicon.
This plugin is especially useful if you’d like to set a Site Icon, but also need to set a unique favicon separate from it.

WP Post Icon vs Site Favicon