Greens might be your best bet. In winter if trees drop their leaves light might be better, enough for greens.

I wish I had a situation like yours for my shiitake mushroom logs. Otherwise I would cut down a few trees to provide light for vegetable crops. I've been in an ongoing battle to plant trees and cut down trees over the last 40 years and even though I don't have trees shading any greenhouse at the present time, the wind blown branches do poke holes in the plastic during hard windstorms.

Thank you for the replies. Yeah I reckon it would be perfect for mushrooms. It's not really practical at the moment to get them cut back there are a lot of trees and in summer the greenhouse is covered by a 30 foot canopy. It's like a rainforest up there lol. It would cost me quite a bit too sort out. In the winter is much lighter up there but as soon as those leaves begin to grow