Conferences
Conferences are a great way to get exposure to new mathematical ideas that you may not otherwise see in your classes. It's usually possible to secure some funding for travel to conferences; VT has a travel grant available for undergraduates.
It's worth noting that you wil probably incur some out-of-pocket travel expenses for conferences -- travel grants are very specific in what they are allowed to cover/reimburse, and there may be a maximum reimbursement allowance which is lower than the actual cost of your travel (only $500 towards a $634 plane ticket, for example).
Below is a (non-exhaustive) list of conferences/conference calendars which may be of interest to undergraduates.
Societies and Associations
The American Mathematics Society (AMS), Mathematics Association of America (MAA), and Society for Industrial and Applied Mathematics (SIAM)
The AMS also maintains a Math Calendar with a bunch of non-AMS conferences in it. Individual conferences may have sources of travel funding; see the specific conference website for details.
Recurring Undergraduate Conferences
There are many annual/bianniel undergraduate math conferences. These are usually regional, and so the hosting university rotates from year-to-year (making it hard to point to a single link that will withstand the test of time). It might be easiest to run a Google search for "undergraduate math conference [year]". Nevertheless, below are some of the recurring ones which are somewhat accessible from VT campus.