Children playing in a park in Wolverhampton discovered the body of a man under some bushes.
West Midlands Police said the primary school-aged children made the "grim discovery" in Coronation Park, Bilston, just before 1600 BST on Saturday.
A spokesman said the death was being treated as unexplained.
He said: "It would appear that the man, who is yet to be identified, had been there for some time. He is believed to be aged around 30 years old."
The spokesman added that a post-mortem examination would be conducted in due course but said police were not looking for anybody else in connection with the death at the moment.