The problem with squash is that it is rejected by so many people that they have no idea of the kinds available. Marrows of two kinds are certainly grown in the States.
Squashes, pumpkins and gourds are all members of the Cucurbita and thus closely related. All of them came from the Americas. Now there are so many selected varieties and hybrids that boundaries are blurred. Summer squash include the yellow (generally necked) and the "green" which include vegetable marrows, pattypan and zucchini. Winter squash are generally rougher-skinned and include acorn, Hubbard, and a host of others including marrow (not vegetable marrow) just to cause confusion. Spaghetti squash often shows up here (inside stringy); I don't know to which group it belongs. In the fall, a lot of winter squash come into the stores with hybrid, patented names, again, causing confusion to the uninitiated. In addition to eating winter squash as Jim Dixon does, the cooked pulp can make wonderful pies, used like pumpkin or sweet potato.