LEDs seem to automatically self-regulate to achieve ideal voltage across terminals
LEDs forward voltage and current are described in the I/V curve:



By limiting the current with the 50kOhm equivalent resistance, you probably put the LED in the region with about 3V of forward voltage (if that is what you measured).

In reality the calculation would be:

120Vrms - 3V = 50000R * i

i = 117/50000 = 0.00234A = 2.34mA

p.s.: IRL don't use a single resistor in series with 120V AC, they aren't normally rated to withstand 200V peak. Use multiple in series. Or don't experiment with 120V AC at all if you are a beginner.

p.p.s.: differences measured IRL can be explained by resistor, LED and AC socket voltage tolerances. (from comments: Also, you'll be measuring rectified AC. Many multimeters don't deal well with that since they do an approximate calculation for RMS values considering a sine wave.)