I struggled to find stuff to put on ours because we'd already lived together for almost 3 years and been in a house for the last 8 months of that. I ended up putting stuff we didn't really "need" on there but was just upgraded versions of stuff we already had. Nice towels and sheets, new silverware since we had like 4 butter knives, stuff like that.
In the end we just ended up getting mostly cash since I don't think most people found the registry (I had a link to it on our wedding website but I think a lot of people missed the website altogether since I forgot to get separate insert cards with a link to it and just had it on the back of our RSVP cards). I was happy with that.