I have a dark spot under my feet, its dry & doesn't doesn't hurt?

Dry sole: Sounds like it might be a bruise or type of callus caused by type of shoes worn or an injury you had in past. It resembles a healing scab but is thicker since its on the sole of the foot.

Get it checked: Although this could be from trauma it also could represent something more serious and is worth getting checked by your pmd, a dermatologist or an foot & ankle md.