These look like a type of Scleroderma "earthball" mushrooms; there are a few locally-native species, though some are more common than others. They are non-pathogenic (don't infect live plants), instead growing on decaying matter in the soil that might be under the gravel. They are harmless to the garden/lawn/driveway and in that respect don't need managing, but if you have any pets, they could be poisonous if ingested, and as such you can remove them if you prefer. (If ignored and avoided instead, they will still degrade on their own and eventually disappear.) Even if removed, they could regrow periodically, as weather permits, at least until their food source is depleted and the fungus itself dies out. You can wear gloves or use a shovel to remove them.

Emily

you're welcome!