I just stumbled across this 2019 National Quilter's Circle Mystery PP Challenge that is still available for free. I didn't have to join anything to play. All the fabric requirements and block patterns are here:
https://www.nationalquilterscircle.c...-requirements/
it does look challenging.
ooooh
and here's another ... this one is a Medallion Mystery Challenge:
https://www.nationalquilterscircle.c...llenge-week-1/