I would however advise that you do not use essays which have been found online to hand in as your own. The reason for this is that most schools, colleges, universities and businesses have very advanced anti-plagiarism systems used to ensure that all work handed in has been written by the individual. These systems will accurately pick up on any work which is not your own; even short copied sentences will be detected. Most educational establishments will fail work with plagiarised content, even in small amount. An entire plagiarised essay would definitely fail and you would likely be punished; expulsion is possible.
If you are looking for essays on particular subjects to help you compile your own work, it is advisable to join an online library. This will give you access to a large selection of essays, journals and books on the topic in question. You should then be able to gather enough information to write the essay in your own words - far less risky in terms of plagiarism, and more satisfying for yourself rather than relying on someone else's work.