Thank you, Jessica. I know I'm not supposed to ask questions of an agent, but this time I'm going to chance it, as the answer will influence any queries I send in the future: I have three finished ms, all in the same genre, but I never know which one to send to an agent. Should I send one and add a note that I have two others? Or stay quiet on the other two?
Again, Jessica, thanks for your quick reply, and if I'm off base just delete and I'll understand.
I don't think it ever really hurts to let an editor or agent know that you have other books that you've written and might be available. That being said, the response you receive on a query letter will be solely based on that query alone. So I would worry less about trying to tempt them with everything and focus on that one thing you think is the strongest. What is the strongest story with the strongest hook and the strongest writing? Put everything else aside and make that your focus.
Also keep in mind that an agent usually assumes that what you're querying is your most recent work so if this doesn't grab her it's unlikely something she thinks will be less polished will.