I used to think everyone called (cobs|bread cakes|rolls|barns) muffins, and it turns out it was just my small town that did it. As in, just my small town, not region, county, etc.
UK regional dialects are summed up really well here because despite listing five different names for a specific thing you still neglected the word I use (baps).
I ask because i'm only familiar with a thread/yarn bobbin, I wonder if it derived from that.
(So obviously those calling them cobs or rolls or whatever else are just wrong!)