Philip K. Dick is widely regarded as one of the best Science Fiction writers ever. He also might have been insane, which would explain many of his stories. Even if you have never read a single one of his stories you have undoubtedly watched one of the many movies based on his books such as Minority Report and Blade Runner.
Now you can read 11 of his short stories for free!!! So if you have no yet checked him out, now is your chance.