Stolen from Reddit
https://www.reddit.com/r/dataisbeautiful/comments/1ftmkwt/oc_foods_cost_vs_caloric_density/
But I loved it. Also this has Shrimp removed, because it was on the OG chart due to an error and this is an updated version.
EDIT: Here is one for protein! https://www.reddit.com/r/budgetfood/comments/1fp2ytb/foods_cost_per_gram_of_protein_vs_protein_density/#lightbox
Yes. Or some other species close to it. I usually forage tree types of walnuts but I don't know their names.
I once found a ornamental Juglans Nigra tree that my city have marked as "American walnut tree" and picked 10 or 15 nuts. It took me days just to open 3. It was tasty though.
Are these types of nuts sold in shops? In never saw anything but European walnuts and the taste and texture are very different.