Do you want to make a raised bed garden. You can take pallets apart and build your perimeter.
Here is a tutorial for above ground planting using pallets. You could expand the sizes if you want larger garden beds. I hope this helps, Yvonne. https://www.hometalk.com/29529869/pallet-wood-vertical-planter
Hi Yvonne: Here's a site that right up your alley. But, before running all willy nilly looking for pallets for your garden, check these sites out to be sure you are not getting pallets that will harm you:
Here is one gardeners idea https://www.onehundreddollarsamonth.com/pallet-gardening-how-to-create-a-wood-pallet-garden/