In accreting situations  small mounds of vegetation or tide-washed debris form  and tend to enlarge as the wind-speed drops in the lee of the mound, allowing blowing sand (picked up from the off-shore banks) to fall out of the air stream.
When a mound forms in an accreting situation, it attracts more vegetation and debris as the wind slows down. This allows sand carried from offshore areas to settle on the mound.