Can anyone help? I'm desperate!

Rosebay this may be a foolish question but have you tried contacting Pottery Barn

Not a foolish question at all - yes, that was my first stop - I contacted Pottery Barn and they no longer have this hardware. I've found several places online that look like they have possible hardware that would work, but they are wholesale and of course won't talk with me when they find out I'm looking for 4 pieces :)

I'm attaching another photo - this is of the bed rail and footboard to show how the pieces fit inside. Like I said, I think I'm missing a cam or some curved part that fits inside the large hole, which is 2" in diameter.

They are called cams. You can check any wood workers supply places like this one:

http://woodworker.com/15mm-x-125mm-kd-cams-mssu-866-497.asp

Lee Valley tools was still kicking a decade ago. they might be still. ebay is another possibility.

Another idea call a small domestic casegood manufacturer and ask for the name and number of their supplier. Perhaps there is one in your area.

Hi everyone - thanks for all of the feedback - I've been pursuing all of these options, and think I have it narrowed down to either a curved washer or something like the zip bolt, or ZINC fasteners. Now to get the sizing just right and I think I'm on my way - bought a pocket size caliper to get measurements and hopefully will be on my way to an assembled be in a week or so. Thanks so much to everyone.

It occurred to me that you might try this company, Rockler Woodworking, http://www.rockler.com/ . Call them and send them the pictures you have posted. I would bet they will have these parts or can get them.