http://www.edibleacres.org
Some plants we've had very positive results with in our chicken yard...
Elderberry for sure
Currants of all sorts, with Black being particularly adept at high fertility and shade
Goumi - They love the fruits and the leaves
(I suspect Autumn Olive would work really well too)
Seaberry
Grapes
Gojiberry
Thornless Black Berry
Western Sand Cherry
Honeyberry
Raspberry
Gooseberry

Surely so many more would work... Please share notes of what works for you.

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Happy growing!