Spinach doesn't have a very high iron content
the whole myth is because someone accidentally got a decimal place wrong. And peas have more iron than broccoli, according to Suggs.

EDIT: wikipedia Popeye the Sailor Man has a strong affinity for spinach, becoming much stronger after consuming it. This is partially due to the iron content being mistakenly reported ten times the actual value, a value that was rechecked during the 1930s, where it was revealed that the original German scientist had misplaced a decimal point in his calculations. In truth, spinach actually has about the same iron content as a lot of other vegetables, and even less than others. Cooked broccoli and cauliflower, for example, have almost double the iron content of spinach.[citation needed]
( Madam Marlboro wonders if you've found her yet, Mon 29 Sep 2008, 22:37, Reply)