Congrats on your first morels of the year! Here in Oklahoma the season tends to hit in late March through April when the ground warms into the 50s and we get a good soaking rain followed by a few sunny days. I usually find them around elm, ash and old apple trees, especially in spots that burned or flooded the year before.
Moist soil and swings between warm days and cool nights seem to trigger flushes, so you really have to watch the weather. Morels grow fast—I've gone back to the same patch 3 days later and found handfuls where there were just pins before.
It's always a joy to see those honeycomb caps after a long winter. Enjoy your haul and keep an eye out for false morels and ticks!