I have read that Ethernet have a header and a trailer, but in Wireshark I can only see an Ethernet header and no Ethernet trailer.
Wireshark only shows what it is passed by the NIC driver - with the FCS truncated. Some NICs specifically allow passing the FCS to the upper layer, see the NIC specifications for details.
There are actually two sets of headers and trailers with Ethernet. Wireshark (or any other tool) can only capture data link layer data (L2 header and payload).
The physical layer's preamble, SFD and IPG cannot be captured without special hardware (on many physical layer variants the IPG is actually filled with idle symbols).
This answer shows headers and trailers in each layer in more detail.