I always see these on Etsy, but they're like $30+. I figured I'll try my hand at it...
You start with a wreath base. I got these at Michaels for $1.99. The yarn was like $3.
Wrap the yarn around real tight, going all the way around.
Took about an hour. Make sure you add a hanger addition. I just used a knotted loop of yarn.
Don't worry too much about little gaps. You're going to add stuff.
The bats are black felt cut-outs. The flowers are the same, with white flower buttons added in the center. The jack o'lantern is actually stuffed. I used my felt scraps to fill it to keep this a green project. Overall time: 3 hours.
I've started on the next one, but this is all I have finished so far.