We don't have a lot of those, so we don't call them much of anything. There are a few places where specific items are sold and bartered like that...mostly vehicle related stuff. [If other parts of this BIG country have different traditions, I am willing to be corrected. Things might well be done quite differently in Alabama than in Colorado or Minnesota).

Much more common are 'yard sales' (or garage sales or 'tag' sales) done on one's own property. This allows more and larger items to be displayed.

Also, there are laws in some places, limiting or forbidding sales on public property...etc.