Like Sedagive said, Hormel makes canned tamales - so does Austex, Kroger has them under their brand, etc.
I don't know where you will find them in your grocery - it "depends" on the store. Some stores put them with the canned chili - some have seperate "Mexican food" sections and will put them there. You may have to ask.
Here is a meal idea:
1 can Tamales
1 can Wolf brand chili (without beans) - or some other brand (or use hotdog chili sauce)
1 can Refried beans
1 can Spanish rice
butter
diced onion (yellow or white)
grated cheddar cheese
Remove the tamales from the can, remove the wrappers, and divide among plates.
Divide the can of chili and place on top of the tamales.
Divide the refried beans among the plates.
Divide the can of rice among the plates. It might be clumped together - so break it apart in your hand ... and a pat of butter wouldn't be bad to add.
Put diced onion and grated cheddar on the tamales and chili. Put about a tabelspoon of butter in the middle of the beans (top with a little cheese if you want).
All quantities are - to taste.
Pop each plate into the microwave for about 2-minutes. Or, heat each part seperately before plating and run under the broiler to melt the cheese - your choice.