Electrons photoemitted by strong laser fields can rescatter, generating attosecond high harmonics. Spectral peaks arise from inter- and intracycle interference of coherent electron wave packets. While intercycle interference is well known, intracycle interference of plateau electrons has not been observed. We present carrier-envelope phase–resolved photoemission spectra from a nanometric tungsten needle tip driven at 1570,nm revealing such interference, supported by quantum orbit and TDSE simulations that elucidate attosecond-scale electron dynamics.