Meus papéis acumulavam-se sobre minha escrivaninha.

English Translation

My sheets piled up on my desk.

In North America no one would say this as a sheet normally means the cloth sheet for a bed while paper may be referred to a sheet of paper or sheets of paper. In this context it would probably be translated as: My papers were piling up on my desk. or My paperwork was accumulating on my desk. Google translate: My papers piled up on my desk.