IIRC, spinach is high in phosphorous, which interferes with calcium absorption. I would start clicking some of the more popular threads in this subforum, as there's a link to what greens/etc are ok.
Ah ok yeah I thought spinach wasn't good. Just wanted to check before I tossed them in.
My mom just came home and said "here this is for little dude." lol I kept stealing greens from her salad drawer.
How does this list sound?
Kale
Collard Greens
Dandelion Green
Mustard Greens
Turnip Greens
Found it. I can't really advise since I just got my beardie a few weeks ago and he refuses to eat anything that doesn't move. Basically all the "pros" here link this site though.