I used a 16 inch doubles wire wreath that I found at Hobby Lobby, but I’ve seen similar ones at Michaels. They are wire, but have funny little sprigs of greenery (in this case the little pine parts were black, spooky good for Halloween) I painted a bunch of faux gourds and pumpkins, then twisted some wire and shoved it into the back of each (most of them it went in really easy, but a few I had to poke a small hole with a pencil to help the wire break through the “skin”) Then I put a little hot glue over the hole/around the wire to help keep it glued in place.
I started with my biggest pumpkins and wired and then glued them around my wreath, then I just went in and kept wiring/gluing until the whole thing was covered. Once I got a bunch in I even started gluing the gourds and pumpkins together where they touched. Since everything is wired in place, it helped it feel extra sturdy. If you are going to hang outside in an area that will see rain I would spray each pumpkin before making the wreath with a clear top coat.