I had that like crazy for at least a month b4 my son was born. The last 2 weeks I went to the hospital twice because it was so bad when I stood up in the morning I thought my water was leaking.
It can come out in bits and pieces too. It does look like a booger. It can regrow overnight (if its just bits and pieces). Sorry! I know that's prob not what you wanna hear lol. U can google it and see what a pic of a mucus plug looks like. Gross, I know...but I was curious so I googled EVERYTHING that last trimester!