I really like the idea of being able to use greens for pesto that are so "easy to grow" that they are almost-weed-like, and that bugs don't like so I don't feel the need to painfully check each leaf is good to eat ( I spend a lot of time doing that). I think nasturtium leaves might be the perfect fit. 

This pesto is simple to make and has a balanced flavour with gentle back notes of nasturtium, the creaminess of the pine nuts, and the salty sharp Parmesan. The omission of garlic is purposeful so as to not overwhelm the softness of the nasturtium. Nasturtium leaves are also a cheap/free prolific replacement for currently out-of-season herbs such as basil. 

I like the soft sweeter tones of this pesto without acidity, however if you are pairing it with something sweet, add juice of half a lemon.

Nasturtium leaf pesto recipe 

Makes 1 cup

30g nasturtium leaves, stems removed

50g pine nuts, raw

50g parmesan, finely grated

100ml extra virgin olive oil

1/8 tsp salt

To make, simply place all ingredients in the bowl of a small food processor (leaves first to make the processing easier) and blend until a smooth consistency.