Walkthrough
At the end of Route 8 moving west is Saffron City. However, since you still won't have access to the town at this time, you will have to use the next underground path. Underground Path 7-8 is a small path that connects Route 7 and Route 8 by going underneath Saffron City. Only a few items can be found here by using the ItemFinder.
Items
Ether: ItemFinder
Potion: ItemFinder
Paralyze Heal: ItemFinder
Awakening: ItemFinder
Burn Heal: ItemFinder
Antidote: ItemFinder
Ice Heal: ItemFinder