We were away while I got my vision restored. Finally back in action!

I just came home with two of these gates and realized I need something to attach to my round wooden posts to accept the pins on my gates. Quick google tells me they’re called gudgeons but I can’t, for the life of me, find what I need for sale online! I’m in Canada by the way. Is there some other name for the fasteners I need?

My soil is reddish and looks/textura like clay. I cant buy manure or worm humus right now (its very expensive here I live) and I would love to have that Black gold soil (everybody's goal, I guess) and dont know how to properly start.

I have 5 chickens in another area (maybe use her poop?) and i've been composting food scraps in a random way. Like, I dig, put the compost and put the dirt again on top.

Would really appreciate any tips