2NL 6max no reads on villain. Both hero and villain have almost the same stacks.
Hero on the BTN with 106s
Action folds to hero, hero raises to 2.5BB.
SB folds BB calls.
Flop: 859 rainbow (no hearts)
BB bets 4BB (pot). Hero calls.
Turn 5 of hearts.
BB bets 1/4 pot. Hero calls.
River K.
BB checks. Hero checks.
BB takes pot w sm random pair.

My analysis is that I made a mistake not c-betting the turn as villains bet is super small. Should I have c-bet the flop with my inside straight draw? All tips are welcome, thanks.

At 2NL I'd expect opponents to be complete calling stations unless proven otherwise (better players will move up stakes fast).

As such, play tight and raise big with a stronger range. Value bet the hell out of it when you have it, shut down when you don't. To get fold equity from bluffing or semi-bluffing you need opponents that can fold occasionally, otherwise you're just bloating the pot with the worst of it.

For this hand:
- Fold pre
- Fold to pot-sized donk on the flop (villain likes the flop a whole lot more than you)
- Fold to turn bet (5/1 odds still too expensive for your gutshot)
- Checking the river and taking your medicine is the part I agree with; at NL2 villain could call with any made hand if you try to represent the K

I agree with everything Big Papa Bear said, especially "fold, pre.". One more thing, your terminology is a little off. You are asking if you should have c-bet the turn or c-bet the flop and it isn't really a c-bet in those spots. What happened is that the BB donk-bet the flop. Basically what that means is that BB didn't have the "betting lead", and normally folks check to the pre flop raiser, when instead of checking the player leads the flop, out of turn so to speak, that's called a donk bet. So we are no longer in c-bet territory when it gets to you on the flop, we are analyzing "how to respond to a donk bet". There is a lot of stuff written on this subject both here on 2+2 and on the greater web. Research how to respond to donk bets. By the time we get to the turn you are no longer in a position to c-bet because you called the donk bet and villain led the turn. The way I would describe your decision on the turn is whether to raise. It's not a big deal, I just thought it might give you a concept to research.

To answer you question about whether you should have raised the donk bet with your gutshot, I wouldn't do it. I wouldn't put any more action in with that hand against that action without a flush draw or an OESD and even then I probably wouldn't raise.

2+2 is a great place to ask questions like these. There are a lot of excellent posters. One more thing, the Micro Small Stakes forum has mostly 6 max players so you could post there as well.

GL, Magnum