It's really hard without consuming dairy. Not everyone would feel comfortable with my food choices as they're a bit odd but here goes...
Breakfast is eggs and a mountain of cooked collards. That way I know I'm starting my day with about 350-400 mg of calcium.
I make seed crackers that have chia seeds in them and I add ground baked eggshells to the batter. The eggshells contain high levels of calcium carbonate. Hard to determine the calcium contents of the crackers but it's likely high.
I eat lots and lots of greens; mesclun salads, broccoli and broccolini, kale, bok choy etc. I might make a smoothie with greens powders; Amazing Grass Original and kale powder.
I'll also add Plantation Organic Blackstrap molasses to a smoothie or my cocoa/herb drink which has 145 mg in a Tblsp. It is high in iron and calcium which are competing nutrients but I'm sure some of each is absorbed.
I drink an herbal tea which has nettles and peppermint amongst other herbs which are very nutrient rich particularly in calcium and magnesium. Again, hard to quantify but the nutrients are there in an absorbable medium.
I do eat quite a bit of salmon and the canned salmon with bones is quite high in calcium. I also eat sardines which I detest and the smothering method I use to disguise the taste would likely not be palatable to most.
Gerolsteiner mineral water has about 130 mg in 12 oz. I let the fizz out for awhile before drinking as I hate the carbonation.
Chicken with the bones. I chomp on the bones to get out some of the nutrients. I then make bone broth with the carcasses. High in collagen and nutrients.
The best hack is Eden Black Sesame Tahini which is super high in calcium. I use it like a supplement. If I'm low, I'll take 1 or 2 Tblsp which has around 350-400 mg. It's a strong taste but if you can't eat it straight, you can smear it on toast with some jam or put in a smoothies.