What should I do if I find a bag by the road that I'm concerned it's a dead body?

So I was walking and found this garbage bag that had flys on it and it was tied up. I kicked at it a bit and it did feel like something limp was in there like it was dead. Tried to untie it as well so might have my fingerprints on it. But yeah a car came up and was yeah someone actually concerned for me and he’s like I’m...