I guess you'll just have to start propagating the stuff you have -- I for one would like a shade-tolerant raspberry because I'm helping a friend set up her garden and it's quite shady (and muddy, ugh).

Squashes are pretty pretty princess who will only grow in full sun?

Though it you've got black walnuts, the thing to plant under them is apparently pawpaws, which can tolerate the juglone that black walnuts put out to kill competitors.