how can you tell if your smoking legal bud

You should take it to your local police department, they will be able to tell you

If it was real fresh like you said, then my guess is that you got someones homegrown, or outdoor grown weed, that had prolly been picked to early. It would look and smell good, but wouldn't get you very high. It could have also been well grown midgrade, I believe I got a bag of this today. It looks good, not tons of trichomes (crystals), smells alright, but only gets you about middies high, not nugget high if you know what I mean.