Research, research, I didn’t do enough of it. Turns out this broccoli is a cool weather plant and these small heads are the plant going to bolt. I’ve collected this much twice and cooked it and it is good: like regular broccoli but a little stronger flavor.
I read that it will produce more heads if you take the main heads off, and there were several plants that hadn’t started heading yet, so I’ll leave the plants alone. If they do what they originally wanted to then, I’ll grow more next year. Hmmm, might even plant it at the right time next year. You live and you learn!