WELL KNOWN PORT NUMBERS (source IANA port-numbers)

nfsd-status	1110/tcp	Cluster status info
nfsd-keepalive	1110/udp	Client status info
picknfs	1598/tcp	picknfs
picknfs	1598/udp	picknfs

Stevens in TCP/IP Illustrated Vol 1 says:
"The NFS server receives client requests as UDP datagrams on port 2049. Although NFS could be made to use the port mapper, allowing the server to use an ephemeral port, UDP port 2049 is hardcoded into most implementations."
But IANA has this entry for port 2049:

shilp	2049/tcp
shilp	2049/udp

RFC numbers (from NIC.DDN.MIL - index)

1904	NFS: Network File System Protocol specification
1833	Binding Protocols for ONC RPC Version 2
1831	RPC: Remote Procedure Call Protocol Specification Version 2
1813	NFS Version 3 Protocol Specification
1790	An Agreement between the Internet Society and Sun Microsystems, Inc. in the Matter of ONC RPC and XDR Protocols
1057	RPC: Remote Procedure Call Protocol specification version 2
1050	RPC: Remote Procedure Call Protocol specification