The bent nail, baling wire or twine / string are common fixings for farmers or workers who moved from horses and not OEM fastenings
Wooden pegs acting as shearpins are frequently used to secure points especially in areas with stony ground, I was reading a bit about Doe triple D drivers, one of whom kept a string of points like a necklace, a supply of pegs and a hammer, once set in the furrow he would climb out on the (reversible) plough and replace missing points on the shares up in the air, the tractor driving itself !!
As to what wood the pegs were made of I don't know but suspect probably Oak or Ash - no doubt there was some old rake maker on Nacton heath who would knock these out for Ransomes at fourpence a gross.
If they are parallel, you need a bit of steel tube of that (or the largest diameter if tapered) but an inch or so longer and sharpen the outside end to a cone (like the wood in a pencil) weld it into a bit of plate near the bottom, and find a vice or block to mount it on vertically.
Cut some green oak or ash to the length of the peg, split it into 'chips' just over the needed diameter sqr. and welt these through the tube with a wooden or hard rubber mallet, (the next one takes the previous one through) you should end up with a pile of little pencils, if they are hard to knock through, counterdrill from the non sharpened end to within 3/4 inch of the top by a mm or so.
Thats how we make rake tines - if you need tapered, whittle a groove in a board with a stop at the end and plane or rasp them down. there is an alternative method where after splitting the chips you take the corners off with a knife and hammer them through a hole just drilled in a steel plate, not had any luck with this method meself
HTH - Have just finished the Ransomes book bought at the recent Norfolk Showground do and don't recall a mention but they may well have made them in the various wood shops at Ransomes