Any round pearls from the wild above 7mm in diameter valuable?

It depends. Is it near round or perfectly round? What is the color? Does the nacre have imperfections? Is it very lustrous or have mild luster, or is it almost a matte? Your best bet, in all honesty, is to take it to a jeweler who specializes in pearls to get the best answer. If its a pearl you found in a local source or on vacation, the value to you will be higher because of the memories associated with finding it (emotional value). If that's the case, maybe buy a nice cage or have it made into a ring or necklace to be passed down along with the story of where it came from. Sometimes in life, the value is more than a dollar amount.