thanks for the responses.
I do have a valid green card and will send the copy. my passport expired 2 years ago and i didnt plan travelling and not planning to travel in near future. however you are right. as soon as "if" i get my US passport i will also go to my consulate and inform them for my dual citizenship and renew my passport. since i was paying fo citizenship application, fees etc. i didnt want to pay another couple hundreds to renew my old passport right now. eventually i certainly will.
My concern is IO might ask a proof that i stayed in the USA ( which i did) during the last two years.
My question is shoud i bring some documents like bills, credit card statements to show i was in the USA and working.
I know they have probably an extensive computer system seeing where i was, or my travel history tough...