I have a shady back yard, however there is a big difference between shade from a brick wall and a forest under story. I think it should be called forest under story gardening. I got the idea from wild ramps noting that these were out about 2 months ahead of the tree canopy. In early spring in my zone 5 I see no reason not to try green onions, chives, garlic and radishes. Garlic planted in fall will have made a good amount of progress by mid spring . All of these can be grown before the canopy develops. In cases where it becomes dappled sunlight, as long as it is early enough salad greens are also quite possible. So in other words a lousy space in summer may be fine for spring.