ASUS A320M-C motherboard
Motherboards for Socket AM4 are not sold yet at the time of writing, luckily the set included a suitable motherboard from ASUS. The ASUS A320M-C is not available through normal means and was delivered in a fully white box, which is why we presume that the board has an OEM-like background.
The ASUS A320M-C is a Micro-ATX motherboard that we'd place in the affordable segment given its feature set. You can also place Zen processors in the AM4 socket, in addition to the Bristol Ridge processors, however you won't be able to use the monitor outputs since Zen processors lack an IGPU. The manual does indicate that it only supports processors with up to 4 cores, it seems that ASUS is cryptically trying to say that the maximum TDP is 65 watts - the Zen processors with eight cores all have a TDP of 95 watts. Given the fairly scanty power delivery design, which consists of six phases and a mini-cooling block, placing an 8-core Zen processor is probably not a great idea anyway.
In addition to the bright white socket you can find two DDR4 memory slots. The actual bracket mounting system has remained the same, however the position of the mounting holes has been changed. Many coolers use their own backplate and therefore they won't fit anymore - most cooler manufacturers offer (usually free) upgrade kits however. In addition to a PCI-Express 3.0 x16 slot, that operates at x8 speed in combination with a Bristol Ridge processor, there are two x1 slots and a PCI slot (via an ASMedia ASM1083) on the board.
ASUS has shopped at Realtek for the audio and network chips: we see an ALC887-VD2-codec and an 8111H-controller respectively. The latter of course features gigabit speeds. You can connect storage devices via four SATA600 ports and an M.2 slot. There are also a couple of internal connectors on the edge of the board, the most noteworthy of these are the USB 3.0-header and the double USB 3.0 header. The board is completed by three fan connectors.
The rear I/O of the board features a range of connectors from the past and present. There are two dedicated PS/2 ports for keyboards and mice and there's even a serial COM port, however there are also four USB 3.0 ports, in addition to two USB 2.0 ports. In terms of video outputs for the internal GPU we have VGA, DVI and HDMI. Last but not least, there are three audio-jacks.