Since each mushroom cost $2, on the first day Keziah and her mom picked and sold 58/2 = <<58/2=29>>29 mushrooms
After picking 12 mushrooms on the second day, the cumulative total became 29 + 12 = <<12+29=41>>41 mushrooms
On the third day, they picked double the previous day, which translates to 2 * 12 = <<2*12=24>>24 mushrooms
It therefore means that over the three days, Keziah and her mom picked a total of 41 + 24 = <<41+24=65>>65 mushrooms.
#### 65