Believe it or not but a package of paper re-enforcements. I have discovered they are wonderful for holding the bobbin thread tail on top of my bobbin. I hate having all those little threads hanging out of my bobbin holder. So I put the loose end of the thread on top of the bobbin and then add the re-enforcement to hold it.
I've also started writing (very small 100% if it's 100% cotton) on the bobbin so I can tell if it's cotton or polyster.
Good luck and have fun !!!