If I include a bookmark with the book do I have to send the package 1st class instead of media mail?  I looked thru help topics and couldn't find anything.

I know when I order books online from an off-price retailer, they ship media mail and include bookmarks.

sometimes what i have done is just stuck it partway through the book. that way if it ever was opened, it would look like it was left there on accident

you are supposed to pay 1st class postage if you include anything that isn't media.  However, you could add 1 regular postage stamp which would be the cost of mailing the bookmark by itself.

I can't remember where in the help docs that is on the USPS website but I know I've read it and I think it has been addresses somewhere in this forum

Actually it's not a paper bookmark that I was thinking of including.  It's metal hook shaped thing with beads (I make them).  I think I'll just send it separately.