There may be a code number on the disk that will tell you the exact year. You can also do an Internet search on either the recording artist or the song title. I suspect that your records were made in the 1940s or early 1950s.
The normall run of the mill record like that normally sells for $1.00 at a flea market. Actually some of the rock and roll 78 rpm records made in the early to middle 50's before and during the change over to 45rpm's sometime sell in the $100's of dollars. But they are few and far between. Yours are as was said earlier more than likely 40's to 50's vintage. I bought an estate a few years back and ended up with about 1000 78 records. still have 999 of them. They make great wall hangers.
DG
That would put a positive id on the years. I have a billboard catalogue that's list'sa just about all the songs and artist by years.The MGM label is late 40's early 50's.
The Victor label is pure 1940's.
DG