My friend/roommate/pseudo-sister decided that she wanted to have a Regency Tea/Picnic to celebrate her birthday, so we whipped up a couple new dresses, turned some dollar store straw hats into bonnets, made some delicious comestibles, recruited friends (also who prepared delectable foodstuffs), threw out some blankets and picnicked.
The standard go-to pattern for Regency dresses for us is Simplicity 4055. Their versions look quite ugly in the photos, and on their oddly Keira Knightley-looking model (even though this pattern was originally released several years before that awful Pride & Prejudice movie -watch the 1995 BBC miniseries... it is the BEST adaptation of the novel).
I used a blue and white striped batiste for the underlay, with a white embroidered voile for the overlay, and solid blue broadcloth for bias tape to finish the neckline and for the sash (I hate when they're not snug enough in the underbust and the empire waist seam rides up). I also put the puff sleeve over the long sleeve variation, and used the edge/border of the voile instead of sleeve binding.
Lacking appropriate Regency style footwear, we went scandalously barefoot.