Example of a mucus plug:

Tiffany • 31 years old w/PCOS. Conceived a girl (born Jan. ‘17) on Clomid. Now forty weeks pregnant with a baby girl with the help of Letrozole aka Femara
I never did find good posts picturing what someone's mucus plug looked like, so I decided to put it out there for someone who is pregnant and curious.  
Disclaimer: The look and color of a mucus plug is different for everyone, but my mucus plug changed over the course of  a few hours: