Not totally sure... but it looks like this might be lightly marbled fondant? It doesn't seem like it's an imprint or anything.. but just that the person colored the fondant a light creamy color and then put a streak of a darker beige/brown... but didn't blend it totally.. and then rolled it out.
perhaps someone else can have other ideas?
I agree with PP. I think it looks like they marbled the fondant also.
For the bowling lane here I rolled two colors of fondant into ropes, put the ropes side by side and rolled them into a single two toned rope, coiled the rope in an oval spiral so it looked vaguely like the cross section of a tree with the rings exposed, then rolled it with a good bit of pressure. As I rolled it I pulled it and overlapped areas that wanted to separate. The end result wound up looking like a single sheet of plywood which wasn't quite what I wanted for my purposes, but would work well on a smaller scale for what you need. To get rid of the plywood look for the bowling lane I just cut my fondant into strips, mixed them around in overlapping panels, then rerolled them into one solid piece.
Thank you so much, I love the idea and I love the bowling cake too. Will need a practice before I cover the final cake but I'm sure it won't be that difficult now. Thanks again
The bonus with this method is that by rolling out a piece larger than you need you can select the specific area of your rolled fondant that has the best 'wood grain' effect. Also, once you've rolled it out to your satisfaction check the back just in case the pattern that develops there is better. When marbling or wood graining you should have a look at both sides of your fondant before deciding which one will be best used as your "top".