Imp Stool and River Betty will be easy to come by but ive never been much of a dragonfly chaser . I probably have 60 Blue Butterfly Wings so butterflies are much more easier to get. The Orange Dartwings are usually above the lakes outside of Morthal right?
In my greenhouse im growing tons of wheat, creeps and red mountain flowers. Riften did restock but i also found a good amount in my house, my kitchen had maybe 10.
The Hall of Dead in Solitude is the one you're referring to. There are over 60 Hanging Moss' there but ive never looked for the Dartwings so i'll have to check it out again. A cool trick i just heard of is casting ice storm over a lake where they are flying and they freeze and drop to the bottom which makes them easier to get.
Human Flesh+Imp Stool+Slaughterfish Egg is probably better poison but Human Flesh is really hard to come by. Same as a human heart which i needed when i created that poison to kill the Ebony Warrior. I'm gonna get the concentrated poison perk now so all the poisons i have now are essentially doubled.