There is a
golden horn, found at
Gallehus in North
Schleswig in Denmark, and which has one of the oldest known
inscriptions in
runes, and in any
Germanic language. It says, in a very early form of
Old Norse,
ek hlewagastiR holtijaR tawiDo. That means, "I
Hlewagastir of Holt made the
horn".
The rune here transcribed R is not the ordinary rolled r, but a sound derived from an earlier Z, and before that from S. (It corresponded to the Latin ending -us and has disappeared today in all Germanic languages except Icelandic.) It is not known how exactly it was pronounced. My symbol D is because if I try to use the proper eth symbol, HTM &edh;, it screws up my browser. The rune for j was formerly believed to be ng (Holtingar).
The Golden Horn of Gallehus, dating from about 400, is the most famous early runic inscription, but is not in fact the very oldest. There is an end-clasp of a sword-sheath found in Torsbjærg, also in Danish Schleswig, which appears to be from around 300. This says owlTuTewaR ni wajemariR, where I'm using T for thorn, and this names the owner as "Owlthuthewar of no ill fame".