Don't put it on the resume or mention it, unless the LOR author has asked for it. The whole point of the LORs is to see the applicant beyond their stats. I can't tell you how many letters I have read when I was on UCSF ADCOM, which simply summarized the already-known academic accomplishments of the applicant.
This is actually bringing up an important point about choosing the person who is writing your LOR. They need to actually KNOW you and speak about you in some interesting and relevant capacity. This means, if you can, go beyond simply asking a prof whose class you aced but had not otherwise interacted with.
Good luck!