Vegan sources of calcium
In addition to the calcium-rich plant sources discussed on other pages (blackstrap molasses and green leafy vegetables,) as well as this surprising but possibly highly effective "calcium" supplement, here are some more good vegetable sources of calcium.
Sisymbrium seeds, whole, dried
Sesame seeds, whole & sesame butter or paste (aka Tahini or Tahina made from ground hulled sesame seeds)
Chia seeds (dried)
Cottonseed meal & flour
While organically grown greens are frequently recommended as a bioavailable source of tooth-friendly calcium and more (see article), it also seems to be true that once salad is covered with oil (such as in salad dressing), it becomes difficult to digest and may be excreted in a similar state as it was ingested (if you are so inclined, study your bowel movement after a meal containing salad with oil dressing, unless you have very strong digestive juices and masticate very well, you may be surprised to actually recognise the salad you have eaten since it is mostly undigested).
For this reason, it may be wise to use raw greens mostly after blending them in a mixer in both sweet and savoury preparations (for instance as a "green smoothie").
As is likely true for most foods, you will get a higher nutrient content and a more balanced mineral spectrum (and simultaneously avoid pesticide, fungicide and other toxic residues) when opting for organic produce whenever possible.
Here are tips how to eat organic "on the cheap".
With respect to milk (for those who use animal products), the only good source of bioavailable calcium seems to be raw organic milk from animals grazing on mineral-rich pastures.