Thanks for the information. In that case you would generally be considered "inadmissible" from the US due to having a marijuana possession conviction. You can try to just travel as a Canadian but there is a possibility that when you do so, you will be asked about the conviction. There is also the possibility that it will not come up at all. If you are asked at any point about any arrests or convictions, you do have to be honest. There is no exception in the law eventhough it was less than 30 grams. However, the good news is that since it was less than 30 grams, if they do ask you about it.. you will be allowed to file the waiver on form I-192. If this is the only issue with the law you have had, then it should be approved.
Good luck to you during this process and I hope this answer has helped you!
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