I'll confess that I don't know a great deal about hammered silver, if someone could help Id this it would be very helpful.
Later today I can grab a book and take a look. Minter looks like Osbert, but I don't know what city he is in off the top of my head.
Okay, it's a type 15 minted between 1125-1135. I forgot that my book doesn't break down the different mints and minters of Henry I's coins, so unfortunately I couldn't tell you the city. If you look on archive.org for the book on Norman coins in the British museum you can scan through that looking for any minter named "OSER" but there might be more than one. My Henry I is from Bury St. Edmunds - while much of the legend on the reverse is obliterated, there was just enough letter combinations that were unique to the minter and mint to figure it out (the "RT" was the particular key - yours clearly shows the minters name, but nothing if the city, so you may only get this if there's only one OSER). England Henry I, r. 1100-1135 (1125-1135) Bury St. Edmunds AR Penny, 17.16 mm x 0.8 grams Obv.: +hEN[R]I[CVS]. Bust facing crowned and diademed, head three-quarters left, sceptre in right hand Rev.: [+]G[ILEBE]RT[:ON]:E[DM]N. Quadrilateral with incurved sides and lis at each angle over cross fleury Ref.: North 871, SCBC 1276, De Wit 3186