Depends entirely on the state/province .... generally,though, it depends on whether you meet the areas "fishing" requirements (licenses,age,etc.) because the law is geared more to resale/commercial usage and whether the species is of "special interest" (rare,endangered,at risk,etc.).
If under the age of 16 (age most states/provinces require you to have a fishing license),doubtful much would come of it other than a stern warning or "probation" if it's a common species ... but parents would be held responsible for any "special interest" fish (seriously doubtful they are as they were so easily collected.
Sunfish species are not hard to keep as long as they are treated like Central/South American cichlids in their housing,filtration.and feeding (they don't require heaters).
There are MANY species of Sunfish .... some are actually very well suited to smaller (10g) tanks longterm.It is more likely that these are the young of one of the larger species though and they will eventually require MUCH bigger tanks (55g minimum) due to size and aggression (which rivals cichlids).
People need to realize that ALL fish (even common tank-raised species today) originally came from a wild environment and it is a matter of proper husbandry to keep them.
As far as POSSIBLE fines/penalties? .... think in the $500 per fish (average) range with possible jail time (more often probation and loss of licenses) depending on HOW the fish is viewed by the respective state/province. Endangered or "prohibited" species go MUCH higher.