The yellow herbs of summer: Calendula.
A woundhealer, internally and externally.
Pick whole flowers every three days while the calendula flowers - until either frost or mildew get the plants. Spread out your take on a layer of newspapers covered with an old bedsheet. On our calendulas there's lots of all but invisible calendula-leaf-green caterpillars, so there's a need to pick up every flower the next day: caterpillars leave droppings, and that's the only way to find them. The larger the droppings, the larger the caterpillar; pick them off one by one and throw them into your garden, they'll turn into one or the other type of butterfly if they survive their caterpillardom.
Or just throw your calendula flowers in the dehydrator right away; those caterpillars will explode in there, though. Sigh. And they would've turned into butterflies, had you not dehydrated them ...
As you're picking new calendulas every three days you'll need to make room on that sheet for the new harvest, every three days. Your 3-day-old take will only take half the space it took when fresh, your 6-day take will only take half the space it took when 3 days old, and your 9-day-take is ready for the dehydrator, set to 30-35 deg. C. (about 90-95 deg. F). Dry calendula in too high a temperature and it'll smell. Very very badly.
Pour your dehydrated calendula flowers into dry glass jars with a tight lid. Half-dry herb will grow moldy in no time at all, so make sure it really is dry.
Keep your dried calendula for too long and the smell will get stronger - but it won't get as bad as calendula that's been dried in too high a temperature. And of course, storing your dried calendula will remove the color from it, little by little, until your previously bright orange dried flowers, after perhaps two years, are barely a light light light yellow, in that glass jar in that dark cupboard.
I haven't usually bothered to remove the green bits of the flowers: most all of my calendula will go into oils and salves, and only a small amount will end up in teas. If you use your calendula more for teas than for external applications, go for picking the petals off the green bits. Or just rub dry calendula flowers between your hands, shake the rubbed flowers in a bowl, and pick handsful of petals off the top of that bowl - the green bits are heavier and will stay in the bottom of the bowl.
Oil: calendula flowers are our best woundhealers, along with plantain leaves (Plantago sp.). Make an oil from the dried flowers (see SJW for details on making an oil, and Goldenrod for details on the "dried herb oil" bit), and make a salve from your oil (see SJW for details).
Food: put fresh petals into salads and similar, for decoration and a bit of color. Calendula petals have been used as a substitute for saffron, but they're a poor substitute, giving neither the taste nor the gorgeous yellow of true saffron.
Tea: use the petals in teas for all sorts of inflammations, internally. Whenever you have urinary tract inflammations, gut upsets, coughs and so on, you also have wounds on your mucous membranes. Calendula to the rescue! Add a bit of one or the other gentle astringent and one or the other mucilaginous plant to your tea blend, and you're set, most of the time.
The green parts of calendula, while edible, will, in teas, irritate the mucous membranes in the throat of a sizable part of the population. You too will stop adding whole flowers to your teas, once the third client with calendula flowers in their tea blend calls you to ask: "Krrr what krrr is krrr in krrr your krrrr tea? Krrrr blend krrrr I krrr can't krrr stop krrrr clearing krrr my krrr throat krrrr! Krrrr."
That irritation isn't dangerous, and it'll stop the minute you add calendula petals, not whole flowers, to people's teas.