Anyone who presents at a conference could receive an e-mail inviting them to publish their research. Unfortunately, disreputable (predatory) publishers sometimes send e-mails to conference presenters, including undergraduate students, who are not aware of the problems caused by disreputable open-access journal publishers.
Undergraduates interested in publishing their research in a journal also need to evaluate the journal to ensure that the journal, and its publisher, are reputable. There are journals that publish undergraduate research. They can be published by honor societies in a field or university presses. The links below provide information on college honor societies, some of which publish journals, and journals that publish undergraduate research.