Here’s a richer black-and-white oak–style wood-grain pattern in pure SVG. It adds more pronounced waves, “growth rings,” and a couple of knot details to evoke a natural oak plank:

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 400">
  <!-- Background -->
  <rect width="600" height="400" fill="#ffffff"/>

  <!-- Main grain waves -->
  <g stroke="#000000" stroke-width="2" fill="none">
    <path d="M0,60  C120,30 180,90 300,60
             S480,90 600,60"/>
    <path d="M0,120 C100,150 200,80 300,120
             S500,160 600,120"/>
    <path d="M0,180 C140,160 160,200 300,180
             S460,200 600,180"/>
    <path d="M0,240 C90,280 210,220 300,240
             S510,260 600,240"/>
    <path d="M0,300 C130,330 170,270 300,300
             S470,330 600,300"/>
  </g>

  <!-- Growth-ring inspirited tighter lines around knots -->
  <g stroke="#000000" stroke-width="1.2" fill="none">
    <!-- Knot 1 rings -->
    <circle cx="180" cy="250" r="20"/>
    <circle cx="180" cy="250" r="30"/>
    <circle cx="180" cy="250" r="40"/>

    <!-- Knot 2 rings -->
    <circle cx="420" cy="130" r="15"/>
    <circle cx="420" cy="130" r="25"/>
    <circle cx="420" cy="130" r="35"/>
  </g>

  <!-- Fine porous texture lines -->
  <g stroke="#000000" stroke-width="0.8" fill="none">
    <!-- Short, random strokes -->
    <path d="M50,75  l10,2"/>
    <path d="M120,90 l8,-3"/>
    <path d="M200,110 l12,1"/>
    <path d="M330,70 l9,3"/>
    <path d="M410,140 l7,-2"/>
    <path d="M550,200 l10,2"/>
    <path d="M300,260 l8,-3"/>
    <path d="M480,310 l11,1"/>
  </g>
</svg>

Features added for oak realism:
	•	Pronounced, undulating grain lines with varying amplitudes.
	•	Knot clusters at two points (the circles) with concentric “growth rings.”
	•	Fine, short strokes to suggest the porous texture typical of oak.

You can drop this into any SVG-aware editor or directly inline in HTML/CSS. Feel free to tweak the positions, amplitudes, or add more knot clusters to suit your design!