Q.forcing branches in winter
My uncle had a plant that he cut branches from in the late fall and brought them indoors and sometimes they developed these billowy white puffy seed heads that lasted all winter. He said it was a Monrovia or Mandevilla “Summmer Snow” bush, but I can’t find anything about them turning into billowy puffy seed heads when brought indoors in the winter. Do you know of any bushes that will do that?

Forcing branches is a fun practice and can give you lots of surprises! I can't verify the type of shrub that you are referencing, but often Clematis vines have an interesting seed head after flowering.
https://www.gardeningknowhow.com/ornamental/shrubs/shgen/forcing-shrubs-to-bloom.htm
https://www.gardeningknowhow.com/ornamental/vines/clematis/growing-clematis.htm