Pine trees are ok to grow seng under or at least white pine is the best and I have found it under other pine as well.
Don, do you remember an article in an old T&PC mag from the late 70s? It talked about growing 'seng under white pine and some enzyme released by white pine needles that accelerated root growth or something like that.
I know I've grown 'seng under white pine with real good results.
I've had the most success by broadcast seeding right before the trees drop leaves. Planting 'seng seed too deep is a common mistake.