If one of your pokemon is kicked out of a gym, you get up to 50 poke coins per day.
But sometimes you miss the notification that one of your pokemon has ben knocked out and so you lose the count of how many coins you have for the day.
Is there somewhere you can see the number of coins you are at for the day?
In a recent update, you can now see how many coins you accrued each day. The amount of accrued coins for a given day will appear on the “today” tab of the research section.