"Toqué las flores."
Translation:I touched the flowers.
I believe you are thinking of this as a 'personal a'. It is not used here because a flower would be considered an inanimate object. The 'personal a' is only for people and pets (except if the verb is tener or haber).
It just occurred to me that maybe you were thinking tocar could take the preposition 'a' in this case. (like 'empezar a' = to start to). If so, than I believe the answer is no. The preposition isn't used.