First up, "Little Plains" is now supported by Coreboot. As explained by the commit from Intel's Marcin Wojciechowski, "This adds a new mainboard: Little Plains for Intel's atom c2000. It was based on Mohon Peak board with some minor changes. This board is not available as standalone product. It is a managment board for Intel Ethernet Multi-host Controller FM10000 Series"
Intel's Little Plains depends upon a closed-source FSP (Firmware Support Package) as is sadly the case amongst most newer Intel boards with Coreboot.
Meanwhile, added by a developer outside of Intel was support for the D510MO, an older mini-ITX board with Atom D510 processor and NM10 Express chipset. However, currently the VGA doesn't work with Coreboot. As part of bringing up this older Atom board under Coreboot, Damien Zammit added native RAM initialization for Intel Pineview.
Plus there's been an assortment of other interesting work going into Coreboot, which you can browse via their Git viewer.