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The groom wears a key boutonniere and the bride has the lock to it on her bouquet.
Vintage Key Boutonniere
Skeleton Key Boutonniere by etsy.com/...
Key boutonniere, Something different for the groom. He wears a key on his boutonnière and She has the lock the key fits on her bouquet
vintage key boutonniere
The groom wears a key on his boutonniere and the bride has the lock on her bouquet