Questions & Answers about Les fleurs sont miennes.
The form of the possessive pronoun must change to match both gender and number. For example:
• If the noun were masculine singular (e.g., le livre), you would say "Le livre est mien."
• If it were masculine plural (e.g., les livres), you would say "Les livres sont miens."
• For a feminine singular noun (e.g., la fleur), the sentence would be "La fleur est mienne."