The Mishnayos of the sixth perek of Berachos discuss all the different blessings which one makes on food, with the exception of the blessing 'borei minei mezonos'. Why is this not mentioned?
The first פני יהושע in Keitzad Mevarchim discusses this question. His suggestion is that the Mishna is only listing berachos that include a lot of different species, to contrast with R' Yehuda who is brought at the end of the Mishna and says each species needs its own specific blessing.
According to Tosefos in the discussion of kimcha d'chiti on berachos 36a, it seems that Mezonos would not be a "פרי" - Tosefos understands that only bread is considered to be a פרי of wheat (See Tos. 38a s.v. האי דובשא that מיני מזונות has עלוי אחרינא בפת and therefore would not be a פרי since it has been processed), as opposed to mezonos which has lost its פרי status through being processed. The Mishna is discussing blessings on פירות, as it begins with כיצד מברכין על הפירות, and therefore Mezonos would not belong there.