Yes, Rwade434 - I have this EXACT same sound coming from the same location - somewhere near the base of the seat between the center console and the seat - it also only occurs when the temp is around 40 degrees or colder. I can make it rattle all day by gently shaking or tapping the seat. If I push on the seat a little bit from the driver's side, the rattle will stop. It doesn't appear to have anything to do with the seat belt.
Did you ever get any resolution? It's been driving me nuts since about 18k miles also-- now it's a couple years later and about 65,000 miles... rattle is getting worse. Dealer hasn't been able to reliably reproduce the sound - and are now starting the "well, it's been a long time, you're out of warranty" etc etc BS response... they have it documented that I brought it in for this rattle at 18k and are still giving me the run-around.
If I had to describe it, it sounds like a coin is stuck in the mechanism somewhere. I've searched and searched and haven't found anything that seems to rattle or make any sound similar. I've tried all reclined, not reclined, forward, backward etc seat positions. Same sound.
2011 Edge Limited with power seats etc.. Same as yours. I've researched the TSB for the creaking sound... 10-17-06 that's been posted in other threads on this forum. I don't think this is the same issue.
It's driving me nuts. If it's at all related to the seat tracks (which are being recalled for other Ford vehicles) Ford needs to step back up to the table and make this right for Edge owners.