I have picked them off the ground, but I would think as long as they are starting to fall, they would be alright to take off the tree. Which ever is easiest. If you see any with a small hole in the shell about the size of a pin head, don't bother with it. There is either a worm in it or he has already eaten the nut. If you plant them in pots around the house, better put them in squirrel proof cages. One year I had some started in pots. They got to be about 10 inchs to a foot, the squirrels dug them out for the nut. I'm not sure which, of the ones I shot, did the deed. I start them in the house, and keep them there till it's time to plant. Sometimes if I find them plentiful, I'll gather up a bunch to put later, in areas that I hunt.
never say never
patience is the companion of wisdom