While routing the traces for the crystals and laying out the board, minimize the loop area of the oscillator signal & the overall trace length. This allows for accurate oscillator operation. It is important to factor in the stray capacitance due to trace lengths, PCB construction, & MCU pins while selecting the external crystal and sizing the capacitors C1 and C2. Depending on the package option, some TM4C129x devices have a GroundX2 signals. Please take a look at the schematic on this screen for how it should be connected.