Uncle Al's list is a good one
I have used sandpaper on
Ipomena noctiflora seeds. They are
incredibly hard coated. You need to rub away for ages. People were amazed that I got them to germinate.
I collected some camellia seeds this year they have a hard coat, I had no sand paper so after forgetting to buy it for a few months I finally put them in a good peaty layer over potting mix and i think they are coming up. the first time I have grown camellia from seed. I just have to live long enough now to see how they flower.
Some Australian plants won't germinate at all without smoke. You can even buy smoky water here to soak the in!
(No wonder most of the rest of the world thinks us strange! My daughter in London was taking pictures of snow last month -bemusing Brit. onlookers).
Some plants (eg Thyme) produces growth inhibitors for other thymes/plants. I guess they grew up/evolved in a rough, dry neighbourhood and first in/up? gets to keep the neighbourhood.
If they all come up at once you're safe.
There are a lot of fungal diseases that kill baby seedlings.
I always plant seeds in a thick sandwich of sterile material ( vermiculite, heat treated "peat") over the top of store-bought seed or potting mix.
Some say chamomile tea will help kill fungus ("damping off" -phytophera??)
I agree about everything you want to eat, something else does too
The possum eats my tomatoes 24 1/2 figs ( I got the other 1/2) and my parsley
He has a 'turf deal' with the snails who eat my chives, leeks, shallots and garlic chives.
I am sure they just divide up the garden between them.
I am always amazed by people who ask
"How did early man find out what plants/ berries etc were edible/medicinal and which were not?"
Sit and watch!! the goose, possum, monkey, snail, duck, sheep etc.
Many are so terrified of plants killing them when in fact it is very hard to make a good, quick, painless, suicide potent from plants. I have researched it extensively.
In one old
NSW Department Of Agriculture pamphlet on poisonous plants chili /chilli featured !!

not
A terrified young mother came up to me in my nursery one day saying her child had just eaten a berry like this (the once she is holding
in my face.)
My "dark side" swung into action uncontrollably and I said
"Not unless he is
VERY allergic to olives."
Anyone used honey, Vegemite, or aspirin or (willow) to promote cuttings?