ますきのこじゃありませんでした
鱒茸じゃありませんでした
masu kinokojārimasendeshita

Noun
Desu Copula

The polite, past negative form of ますたけ

1. Was not a mushroom of trout.; Was not trout mushroom.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana