I am not endorsing these — I’ve never held paper copies in my hands — but here’s a few nightshade-free cookbooks:
http://www.nightshadefree.com/cookbook/
http://noarthritis.com/arthritisbook.htm
http://noarthritis.com/cookbook.htm
http://www.amazon.com/Nightshade-Free-Pain-Michael-Fowler/dp/097977280X/ref=sr_1_3?s=books&ie=UTF8&qid=1351967535&sr=1-3
http://www.amazon.com/Carolines-No-Nightshade-Kitchen-Arthritis/dp/1432797166