The charity is called This Is My Brave ... and Jamie Lynn made it clear it was near and dear to her heart by pledging a share of the profits from her upcoming memoir to the org.

Well, the charity said no thank you ... "We hear you. This Is My Brave was recently recommended to be a beneficiary organization for the proceeds from Jamie Lynn Spears' upcoming book. We have made the decision to decline the offer of receiving proceeds from the book sales."

Britney has now famously railed on her sister for leaching off her fame and not helping her when she was down. Britney seemed very upset Jamie Lynn was writing a book at all, the working title of which was "I Must Confess" -- a lyric in Britney's "Hit Me ... Baby One More Time." The book is now titled, "Things I Should Have Said" ... still a clear reference to Jamie Lynn's relationship with her sister.

Britney has warned her little sis and her parents that they should be nervous if she does an interview.