<ul class="usa-accordion-bordered">

    <li>
        <button class="usa-accordion-button" aria-expanded="true" aria-controls="b-a1">
      First Amendment
    </button>
        <div id="b-a1" class="usa-accordion-content">
            Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress
            of grievances.

        </div>
    </li>

    <li>
        <button class="usa-accordion-button" aria-expanded="false" aria-controls="b-a2">
      Second Amendment
    </button>
        <div id="b-a2" class="usa-accordion-content">
            A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

        </div>
    </li>

    <li>
        <button class="usa-accordion-button" aria-expanded="false" aria-controls="b-a3">
      Third Amendment
    </button>
        <div id="b-a3" class="usa-accordion-content">
            No Soldier shall, in time of peace be quartered in any house, without the consent of the Owner, nor in time of war, but in a manner to be prescribed by law.

        </div>
    </li>

    <li>
        <button class="usa-accordion-button" aria-expanded="false" aria-controls="b-a4">
      Fourth Amendment
    </button>
        <div id="b-a4" class="usa-accordion-content">
            The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly
            describing the place to be searched, and the persons or things to be seized.

        </div>
    </li>

    <li>
        <button class="usa-accordion-button" aria-expanded="false" aria-controls="b-a5">
      Fifth Amendment
    </button>
        <div id="b-a5" class="usa-accordion-content">
            No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public
            danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due
            process of law; nor shall private property be taken for public use, without just compensation.

        </div>
    </li>

</ul>

Add the usa-accordion-bordered class to your .usa-accordion to enable the visual border.

<ul class="usa-accordion{%
  if accordion.variant %}-{{ accordion.variant }}{% endif %}"{%
  if accordion.multiselectable == true %} aria-multiselectable="true"{% endif %}>
  {% for item in accordion.items %}
  <li>
    <button class="usa-accordion-button"
      aria-expanded="{{ item.expanded | default('false') }}"
      aria-controls="{{ accordion.id_prefix }}{{ item.id }}">
      {{ item.title }}
    </button>
    <div id="{{ accordion.id_prefix }}{{ item.id }}" class="usa-accordion-content">
      {{ item.content }}
    </div>
  </li>
  {% endfor %}
</ul>
package:
  name: uswds
  version: 1.4.1
uswds:
  path: ../../dist
accordion:
  items:
    - title: First Amendment
      id: a1
      expanded: true
      content: >
        Congress shall make no law respecting an establishment of religion, or
        prohibiting the free exercise thereof; or abridging the freedom of
        speech, or of the press; or the right of the people peaceably to
        assemble, and to petition the Government for a redress of grievances.
    - title: Second Amendment
      id: a2
      content: >
        A well regulated Militia, being necessary to the security of a free
        State, the right of the people to keep and bear Arms, shall not be
        infringed.
    - title: Third Amendment
      id: a3
      content: >
        No Soldier shall, in time of peace be quartered in any house, without
        the consent of the Owner, nor in time of war, but in a manner to be
        prescribed by law.
    - title: Fourth Amendment
      id: a4
      content: >
        The right of the people to be secure in their persons, houses, papers,
        and effects, against unreasonable searches and seizures, shall not be
        violated, and no Warrants shall issue, but upon probable cause,
        supported by Oath or affirmation, and particularly describing the place
        to be searched, and the persons or things to be seized.
    - title: Fifth Amendment
      id: a5
      content: >
        No person shall be held to answer for a capital, or otherwise infamous
        crime, unless on a presentment or indictment of a Grand Jury, except in
        cases arising in the land or naval forces, or in the Militia, when in
        actual service in time of War or public danger; nor shall any person be
        subject for the same offence to be twice put in jeopardy of life or
        limb; nor shall be compelled in any criminal case to be a witness
        against himself, nor be deprived of life, liberty, or property, without
        due process of law; nor shall private property be taken for public use,
        without just compensation.
  id_prefix: b-
  variant: bordered