This arXiv preprint (not yet peer-reviewed) models dynamically formed eccentric stellar-mass black hole binaries across Galactic field flybys, nuclear Kozai-Lidov cycles, and globular-cluster N-body interactions. The simulated catalog yields roughly 36 Milky Way sources above SNR 1 for a 10-year LISA mission, dropping to only 1 above SNR 50, while predicting a local merger rate of about 9 Gpc^{-3} yr^{-1} and hundreds of faint extragalactic mHz signals. Unlike circular-binary assumptions in standard LISA global fits, individual harmonics from these eccentric systems can be resolved separately yet risk biasing chirp-mass estimates if misidentified. The work extends LIGO's observed population by tracing the same binaries back to their mHz precursors, revealing formation-channel-specific eccentricity distributions that current LVK analyses largely overlook. Limitations include reliance on population-synthesis assumptions rather than direct observations, waveform convergence validated only below 10^3 solar masses, and omission of potential selection effects in dense-cluster environments. Synthesizing this with LIGO's GWTC-3 catalog (which shows possible eccentric candidates) and earlier dynamical-channel studies (e.g., Antonini et al. 2017 on Kozai-driven mergers) highlights an emerging multi-messenger pathway: LISA detections could statistically constrain the fraction of cluster versus field origins long before the binaries enter the LIGO band.