Those orchid plants are very popular lately, at the grocery stores, big box stores, etc. No wonder - nice mark-up on a very showy plant that probably won't bloom again for a few years or ever. So buy another one to get those wonderful blooms again - nice cycle! Yeah, I've done it.
As for any tradition of giving flowers on the 4th, I've never heard of it but any place that sells plants is bound to have a display of red, white, and blue (purple?) petunias to encourage you to plant a patriotic display!
Good buy on your wilted plants, I look for them too.