What are these "rivets" and why are they not flush with the fender?

For the first time I noticed what look to be like "rivet heads" sticking up about an 8th inch, and the other two rivet heads are flush with the steel. These are located on the top of the fender well on the passenger side.

Are these working loose, or busted? What are they hooked up to?

Thanks

 

Honestly looks like they are being used to “plug” holes for options that your truck didn’t come with

 

Look like hole fillers that would be removed to install some type of option

Maybe an ABS module if you don't have that?

 

those are holes for ABS and factory cruise. looks like a previous owner came up with the idea, the factory leaves them unplugged