The Wild Boar Farm folks, from Suisun Valley, refer to these as Evan's Purple Plum tomatoes. They also describe their tomatoes as,"Soon to be world famous." I've eaten a lot of tomatoes this year and this was the first time I felt I had to photograph and come up with words.
The flavor is appropriately sweet and tart, and manages to be meaty without the starchy density of some varieties. In smaller tomatoes of this type, the seed and juice to flesh ratio is probably more akin to a cherry tomato than a traditional plum.
What got me was the incredibly deep hue of the tomatoes --an intensely dusty purple and red-- and the blemishes on the fruit. Even the heirlooms I pick up at Berkeley Bowl or from other vendors at the Grand Lake Farmers' Market adhere to a more traditional notion of aesthetic appeal.
Some of this may be self-inflicted; if I'm dropping 4.00 to 6.00 a pound on produce, I do expect it to be pretty. Something about these Purple Plums though redefines the terms of that expectation.
Rather than some idealized notion of a tomato, they are a tomato that appears to have come from a specific place at a specific time - a kind of vegetable terroir that is only heightened by their being in the last week of the season.