Frederick County Public Libraries will accept donations under certain conditions; please use the following link to determine if FCPL is the place for your donation:
Donate Books and Other Materials | Frederick County Public Libraries (fcpl.org)
Wonder Book has three locations:
The stores accept donations of books and will sell them individually or through the "Books by the Foot" program, donate them, or recycle them if necessary (#BookRescue - Wonder Book (wonderbk.com). You may contact Wonder Book using customerservice@wonderbk.com or 301-694-3547.
Better World Books (BWB) is a company that accepts donations of books and relocates, donates, sells, and recycles books. There are drop boxes in Maryland and Virginia (Individuals - Better World Books Services). Many public libraries send discarded books to Better World Books; if a drop box is not near you, contact your local library branch to see if they use BWB.