thekctermite got it! A quick Google came up with both solutions.
Not sure about quantity. Hopefully you don't have to buy a bag of 50 or anything:
However, if it's not cost effective to get a single (or few) plugs, get yourself a scrap piece of hardwood. Hopefully you have some left over. Now get one of these drill bits in 1":
You'll create your own plug by boring out a section of the scrap wood with this. Now you have a plug that can be glued and pressed in. After it drys, sand or chisel flush.