No seam with this cast on!
Good tutorial:
Knitting Help - Judy’s Magic Cast-On (I love VeryPinkKnits tutorials - they’re all excellent):
https://www.youtube.com/watch?v=GV9UaFgZ6Q0
Thanks! Knitpicks is a good site too. There are lots of good sites (and many bad).
https://tutorials.knitpicks.com/
Here’s a super easy circular cast on for itty bitty circles. (good for top down hats)
https://tutorials.knitpicks.com/circular-cast-on/