As Jerrybo66 above mentioned, the old cast iron pans are much smoother than the modern ones. They used to machine the iron smooth on the food surface after casting. Now, they sell them in the as-cast rough condition. It's actually a pretty good surface for as-cast, but still.
There is a solution. Put a coarse grit flap wheel on the angle grinder, your eye and ear protection on, and gloves, and smooth that surface down. You can not do this if you have a deep pot, but a skillet or Dutch oven will work fine. Now you will have a raw iron surface that will rust very quickly if you don't oil it right away, so you should just season it immediately, using the Crisco or oil in an oven or gas grill method, or whatever is your favorite.
I know that this works well, as I did it with several pots and pans in a collection given to me by my daughter many years ago. It was a Wenzel brand set in a wood crate, and was extremely rough, I think Chinese junk. Now it works as well as any of the antique Griswolds, but is sure isn't as pretty.
This is drastic, but if you have the stomach for it, it really works well.
Mainly, have fun cooking with your iron, and pass it along to the next generation.
:)