Does anyone know that if US immigration has requested for birth certificate to process your green card will they accept the birth certificate issued by the Nepalese Embassy in Washington DC?
Has anyone submitted one from DC and has been accepted?

No, Nepalese Embassy can't provide you the Birth Certificate. You should send record from Hospital where you were born. If you don't have hospital record then you will have to get it from Ward office where you are born. Also, make sure your birth record is coming from Registar of ward office.

Contact the ward office, they will probably know what you're are looking for.

Good luck with your Green Card.

US

Nepali Embassy in Washington DC does issue the birth certificate, it's stated on their website. I did get a birth certificate from them. But my question is will the US immigration accept that? Any personal experience will be greatly appreciated.

If you submit that Birth Certificate, there is big change you will get RFE on it. The thing is these Immigration Officer are used to seeing Indian Birth Certificate which they actually make it from Registar, so they expect the same from Nepal too. I submitted the regular Birth Certificate and I got a RFE on it.

Good Luck

US