Identify bulb plant

[sage]

I have this blub plant since several years....one fine morning it bloomed. Such a delight it was fr me...it was very fragrant as well. Plz tell me its name.
It flowered in late august. Plz also guide me when does it flowers i mean season. The rest of plants are just growing since years but never flowered. They are just concentrating on the baby plant growth but not on flowring...

[Kaleem]

Hymenocallis