im ngl oomfie i dont rlly think ab these things like AT ALL , but im so sure nagisa knows the meaning behind basically every flower known to man
i think she'd either give ibara roses or red camellias - not only do they have symbolism that mayches ibara as well as nagisas thoughts ab her but its also RED !! i love red
however apparently red camillias r hard to find, so probably roses or she may literally see a pretty looking flower on the ground n go ''this reminds me of ibara, i want to give it to her'' and then she gives it to her, which isnt rlly buying flowers but ykk >_< this made me hc nagisa as a flower enthusiast