Here are 15 plant-based foods and their protein density per 100 grams.
1 Spirulina (57 gr per 100 gr)

2 Nutritional Yeast (46 gr per 100 gr)

3 Hemp Seeds (38 gr per 100 gr)

4 Peanuts (26 gr per 100 gr)

5 Pinto beans (20 gr per 100 gr)

6 Tempeh (19 gr per 100 gr)

7 Chia Seeds (16 gr per 100 gr)

8 Quinoa (13 gr per 100 gr)

9 Edamame (11 gr per 100 gr)

10 Lentils (9 gr per 100 gr)

Also significant:
11. Green Pea (4 gr per 100 gr) Source
12. Corn (3 gr per 100 gr) Source
13. Broccoli (2.5 gr per 100 gr) Source
14. Avocado (2 gr per 100 gr) Source
15. Spinach (3 gr per 100 gr) Source
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Sources
(1 to 10) Read more about plant-based proteins on this post from Nutritious Stripped.