The quantity of a dime bag tends to range from 1/16oz to 1/8oz depending on location and quality of the marijuana. It’s about one-to-three medium-sized joints.
As to the OP, the real-world consequences of possession really do depend on the officer involved and the area of the country. Attitudes seem to vary drastically even within a single state. In New Orleans, they’ll most likely just take your pot if it’s a reasonably small amount. In rural areas, it’s not so pretty. A guy I met a met a couple of times was once caught in tiny Bayou Vista with just rolling papers - no weed, but then no tobacco, either. Stupid cops hauled him in for parapharnalia for something he had bought at a damn convenience store.
A few years ago, I was on a Greyhound driving through Mississippi. The bus was pulled over by the police and drug dogs were brought out to smell the luggage.
After a minute or two, I could hear a bit of commotion outside. The bus driver stepped back on the bus and said “They found something,” just loud enough for a few of us to hear.
My heart skipped a beat as I remembered the resin-encrusted pipe in my luggage. Uh oh. I was on the edge of my seat for about 15 minutes, then finally the cops just walked away and the bus was allowed to leave.
When I got home, I could tell that they had definitely been in my luggage, but my pipe was still there. I guess they didn’t figure it was worth the hassle.