Definitely - using mate references helps, but with the hex shape you would need to get creative and add an axis and or use the hex round sketch, do it in both parts, however I'm thinking by the time it takes to set those references up, you could almost be done with the mates. I would insert all the rivets that can't be patterned and make all the ones on the same plane coincident to the top and mate one in position with the plate (up-down), then all the rest will follow, now all you need to do is one by one select the round part of the rivet and the hex sketch round and mate each one concentric, then lock the rotation.
Fully constrain your first one, then use sketch pattern.
If any of the holes were created with features such as Linear Pattern, or Hole Wizard, then the "Pattern Driven Component Pattern" can be a big time saver. See 2017 SOLIDWORKS Help - Pattern Driven Pattern if you're not familiar with it.
Craig a good answer, thanks
I put dots in the middle of hexagons and manually adjusted their configurations, so it succeeded with the sketch driven pattern.
I'm using SW 2014, was not successful Pattern Driven Component.
Thank you for your help.