Common Nouns:
* Bague: Ring
* Baguette: Baguette (a type of bread)
* Banane: Banana
* Banque: Bank
* Bâtiment: Building
* Beauté: Beauty
* Bicyclette: Bicycle
* Biscuit: Biscuit
* Boîte: Box
* Bonheur: Happiness
* Bouche: Mouth
* Bouteille: Bottle
* Bras: Arm
* Bureau: Desk
Less Common Nouns:
* Balcon: Balcony
* Balle: Ball
* Barbe: Beard
* Bassin: Basin
* Batterie: Battery
* Bibliothèque: Library
* Billet: Ticket
* Blanc: White
* Bleu: Blue
* Bonnet: Hat (type of)
* Bord: Edge
* Boulevard: Boulevard
* Bouton: Button
* Bruit: Noise
* Brume: Mist
This is just a small sampling of French nouns starting with "B." There are many others!