The acorns are caused from an injury when the animal was in the velvet. The soft, thin tips of the antlers get bumped, causing a small crack or break. The blood flow is still good, because the skin/velvet isn't torn. The antler growth continues and the bone/tissue is filled in and creates a bump in the antler. If you have ever broken a bone in your body and looked at the before and after ex-rays, the break will look a lot like the acorns on deer and elk. You will see it a lot more in heavily wooded areas, where the animals may bump their antlers on low hanging branches, moreso than farmland/flatland bucks. I have a couple of elk and a couple of mule deer with them. Flinch
