Octagon fill

<svg class="bi bi-octagon-fill" width="1em" height="1em" viewBox="0 0 16 16" fill="currentColor" xmlns="http://www.w3.org/2000/svg">
  <path d="M11.107 0a.5.5 0 0 1 .353.146l4.394 4.394a.5.5 0 0 1 .146.353v6.214a.5.5 0 0 1-.146.353l-4.394 4.394a.5.5 0 0 1-.353.146H4.893a.5.5 0 0 1-.353-.146L.146 11.46A.5.5 0 0 1 0 11.107V4.893a.5.5 0 0 1 .146-.353L4.54.146A.5.5 0 0 1 4.893 0h6.214z"/>
</svg>