Sorry they are all just rocks, just because a rock fits in your hand or has a strange shape doesn't make it an artifact.. No signs of working by man, just nature.
If you learn how to recognize what the work of man looks like on a stone there is no need to look for certain shapes doing that just ends up creating a big pile of rocks for you to take home.
Furthermore 90 percent of the time you're not going to see the entire artifact as it is partially covered so you need to learn how to spot the right material and the small signs of workmanship to be successful on a regular basis hunting for a Native American artifacts