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I know i have a sense of seasons driven by how daylight behaves, that's different from how the US news media anchors the beginning of seasons to the equinoxes and solstices.
Think of a sine wave: one cycle includes the crest of the wave and the trough. That crest and trough are the solstices. Where the wave crosses through the line that describes the point between the peak and trough, that's the equinoxes.
You may have forgotten your math (is it in trig?), but if you take the derivative of the sine wave, you are getting the rate of change. And the derivative of the sine wave is the cosine -- just shifting the wave back a quarter cycle. The solstices now end up on the line: those are the points where the change in day length crosses from positive to negative. Equinoxes are the peak and trough: those are the maximum rates of change.
Spring, as i in the northern hemisphere think of it, begins in February as plants wake up and respond to the lengthening days. That's midway between the solstice and the equinox, and the rate of change in day length is picking up. The equinox comes, and the days are at the fastest rate of change. At May 1st, we're (roughtly) halfway between the equinox and the next solstice: now the day length change is less dramatic day to day. For the next quarter of the year the day length differences won't be as dramatic as they have been day to day. Over the next six weeks at my latitude we'll get less than an hour more of daylight 56 more min), whereas over the previous six weeks we got 92 min.
For me, i think of this as the beginning of summer.
Trees are all leafed out. Roses are blooming, wild blackberries are blooming everywhere along roadsides and in fallow fields. A single peony of the many rhizomes transplanted late in winter has bloomed, punctuating the garden with a bright pink dot. The irises are amazing this year: dark purple falls and yellow standards. Brassicas have gone to flower with clear yellow flowers. Chives and a native onion have lovely pale purple flowers. Squash and corn are sprouting, my tomato and pepper starts are late.
I've no idea what's going on with the fava beans, but their white and black flowers along the main stem are fascinating. I should be eating more of the lettuce plants i purchased before it starts getting too hot. The potatoes should bloom soon, and then i can start raiding to see if the production of potatoes is prolific enough to make having new potatoes worth while. (In other years, it really seemed it would be better to let the few potatoes get big to get a decent return on the investment.