Some unique food from Bihar
Gaya: Tilkut, Anarsa (sweets, desi, famous)
Baadh (near Patna): Laai (a dry sweet)
Nalanda: Khaja (dry sweet; much loved)
(1st 4 pics)
Maner (town near Patna): Boondi laddoo
Deogharh: Pedaa
Patna: Spciy chäat & samosa ++ https://twitter.com/rockyandmayur/status/1273693327490088960

(pics 1, 2: Maner Laddoo and Deogarh peda)
All towns: Spicy Ghoogni (black gram). Generally eaten with fried flatten rice, or even as "chaat", or with poori. (Pic 3)
All homes of Bihar: Thekua (pic 4), Pedakiya, Peetha, Litti-chokha, Kadhi-badi, etc
(Can't be done in tweets) :)

(Cont. in images)
Pic 1: Pedakiya (filling "khoya" or "khyoa+suji")
Pic 2: Peetha (shell: Sooji, rice flour, wheat flour, any variation; filling: pulses+spices; steamed)
Pic 3: Kadhi-badi (the badi, unlike in north, isn't pakora; fluffy, very tricky to make)
Pic 4: Litti chokha

More Bihari food:
Khichdi (spicey, not bland; eaten with dahi, papad, ghee, pickles, mashed potatoes )
Dahi-churaa-gud (hassle free, wholesome, oil free)
Kachori-aloo bhujia: unhealthy but sooo tasty
Kheer-dal poori: generally had in this season, hence mangoes for dessert