If you found these on the surface chances are there are older ones waiting to be dug up. Generally the deeper you dig the older stuff becomes. Have fun and good luck!
Here is a little info on your Owens mark-
Diamond superimposed over an oval [letter O] and an I..............Owens-Illinois Glass Company, Toledo, OH (head office) and other plant locations (1929-to date). Two examples of the mark are shown here. This mark was used from 1929 (possibly not actually engraved on molds until early 1930) up to c.1957. As there was a gradual changeover to the 'new' trademark (with the diamond removed) which occurred over a period of four or five years (beginning in 1954), some bottle molds already in use were not re-engraved until as late as 1957 or 1958. (I have a soda bottle dated 1959 with this "old" mark!). However, after 1958 the great majority of O-I bottles carried the "new" trademark, which was simply an I inside an oval. (See "I inside an O" mark). On very small bottles, the mark may be indistinct and the "I" may be invisible, or just a tiny dot. On the typical bottle, there is usually a number to the left of, to the right of, and below, the trademark. (Note: This arrangement is the most commonly seen, but some bottles, such as liquor flasks, are marked in other ways and so are found with a different code configuration.) The number on the LEFT of the diamond logo is the plant code number, the number on the RIGHT is a date code, and the number below the logo indicates the mold cavity or serial number. Examples: plant code #2 stood for the Huntington, WV plant; "3" was the Fairmont, WV plant; "7" indicated Alton, IL; "9", the Streator, IL factory; "12" was Gas City, IN; "14" was the Bridgeton, NJ plant, etc. Some of the numbers have been re-used for other plants opened in later years, however.
Here is some of the plant code numbers-
http://www.angelfire.com/tn/traderz/owens.html
