A considerable diversity of exceptionally-well preserved Cretaceous gymnosperms has recently been characterized by several research groups across the world. Many of these fossils have ovules/seeds enclosed in extraintegumentary structures and the information they provide has initiated vigorous discussion and hypotheses on Mesozoic seed plant evolution and structural homologies. Here we contribute to this research focus by characterizing a permineralized seed-bearing structure from the Campanian Holz Shale Member of the Ladd Formation, California, USA. The specimen was studied via the cellulose acetate peel technique and a 3D reconstruction rendered in Avizo. Additionally, we assessed the affinities of this fossil with systematic comparisons and phylogenetic analyses using multiple seed-plant matrices. The studied fossil is a cylindrical, yet complex ovuliferous structure that we interpret as a highly modified megasporophyll. The proximal third of the megasporophyll is longitudinally folded (plicate) towards its abaxial side, in which the opposite margins are fused to one another (via secretion) forming an cup-like base. Just distal to this region, the megasporophyll divides into two free lateral lobes that run parallel to one another and form the outer wall of the cylindrical megasporophyll. The corresponding opposite margins of both lateral lobes abaxially fold towards one another, but do not fuse, and run adjacent to the fused margins of the cup-like base. Within the interior of the megasporophyll and near the junction of the lateral lobe divergences, three smaller, yet fertile, lobes diverge and form a single row. The center lobe diverges from the inner surface of the cup-like base while the other two fertile lobes diverge from the inner surface of each lateral lobe. Each lobe has a single abaxially located inverted ovule and laminar tissue that partially covers each ovule. The distal end of the megasporophyll is missing from the saw cut that exposed the specimen. The vascular pattern in the megasporophyll is pinnate, with a main bundle that extends into the central fertile lobe. Proximal to the central lobe, the main bundle produces two successive daughter bundles that supply the lateral sterile lobes. Within the lateral lobes a single trace diverges inwards from the daughter bundles and enter the respective fertile lobes. Well defined phloem gaps indicate abaxial position of the inverted ovules. The integument is vascularized by a single bundle that runs the length of the ovule. The phylogenetic position of this fossil is recovered in alternative placements in each analyzed matrix, a phenomenon that also occurs with other cupulate gymnosperms from the Mesozoic. Thus, its relationships are currently unresolved. Our preliminary systematic comparisons indicate that this fossil is most likely distinct at the ordinal level, highlighting a striking level of potential convergence of ovule enclosing structures and strategies across Mesozoic cupulate gymnosperms, Gnetales, and angiosperms. While there are outstanding issues regarding the homology of seed enclosing structures, this work  highlights that there still are novel gymnosperm clades that have yet to be recognized, some of which may continue to blur the lines between gymnospermy and angiospermy.