The writers of the "coumadin cookbook" castigate avocados as being totally inconsistent in the amount of Vit K contained. They suggest we eliminate them from the diet. I won't; but I'm cautious and treat them more carefully than I used to. I believe they say the same thing about artichokes (don't bank on this; but I think it's the case).
I think the most important thing is to know what's high, what's problematical, and what's basically free. If you like spinach salad, unless you plan for it, you're better off mixing the spinach with inside leaves of iceberg.
Probably most of us don't have a lot of problems on an ongoing basis; occasional mysterious blips in the inr. But it doesn't hurt to know where the traps lay.