I have a lot of chickpeas, various types of beans, some tomatoes, and almost out of sweetcorn.
All get used quite frequently, even without a lockdown situation - DD makes a nice bean taco dinner with the beans and some corn, fried up with some fajita seasoning, and served with wraps, tomato salsa, guacamole, crème fraiche/sour cream, sliced tomatoes/lettuce, and grated cheese. Most of that is still doable from storecupboard ingredients - there is even long life guacamole and sour cream in the Mexican shelf in supermarkets!!
I usually have a couple of different tins that go into Chinese stir fries - bean sprouts, bamboo shoots, water chestnuts etc. These can help to stretch out whatever mixture of the last half a pepper, 3 mushrooms, 1 carrot, an onion, few leaves of cabbage or handful of brussels sprouts.....as a vegetarian meal, or include whatever meat/fish we have, even if that's a mix of a thinly sliced piece of leftover roast pork (from freezer), and lamb (from freezer), and some fresh chicken or some prawns (fresh, frozen, tinned) for a wide variety of stir fries.
I've never tried tinned mushrooms, but I get dried ones from the Chinese supermarket and use them in stir fries too, but mostly to make things like mushroom risottos. Again, not necessarily a lockdown dish, but the variety may be reduced in lockdown. If you carefully pour the water used to rehydrate the mushrooms into a pot afterwards (slowly, so any dusty residue/grit from the mushrooms doesn't go into the pot), you can heat that up and use it as part of the stock to cook the rice for an added hit of flavour and less actual stock needed.
I also have a couple of jars of olives, sundried tomatoes and peppers which are good for salads.
We love tinned pears, usually just on their own, but I am trying to do some baking with them too. And peaches.
In terms of other ways for longer lasting fruit and veg:
Frozen can be great if you have freezer space. We much prefer petits pois to "peas" as they are smaller and more tender. I'm not great about keeping frozen veg otherwise, but most seem to be fine that I have tried. Smoothie mixes are good too for fruit - either to make smoothies or to have chunks defrosted and served with icecream or similar, or to dollop on top of a meringue with cream - either mago based ones, or berry based ones.
Onions last ages in a cool, dark cupboard - well beyond the week. Same with garlic, although that is trying to sprout at this time of year. And potatoes.
Cauliflower and carrots tend to last well in the fridge for 2-3 weeks. Also broccoli and cabbage are relatively long lasting.
Even peppers, mushrooms, courgettes, mangetout, sugar snaps, French beans, etc should all last at least a week relatively ok. The fastest of those to need using up would be mushrooms.
I keep tomatoes out of the fridge, and they generally last a fortnight or more.
And in the bowl on the table, I have oranges, apples, kiwis, lemons, limes (and a butternut squash), most of which last weeks and weeks. The fastest fruit that needs to be eaten from there is bananas (any that go black get used in banana bread, and can be frozen to use later if you don't have enough or the time to do it when they need to be used). The fastest fruit generally needing to be used are berries, which we keep in the fridge - if they start to be less desirable, I whizz them in the smoothie maker with no juice and freeze them (in ice cube trays) as pure berry puree, to add to smoothies later.