Do you mean compounds like this?
somehow
someone
something
somewhat
My nearest dictionary (American Heritage III) lists eleven.
Some words you can add to "frost" are: icy, cold, winter, chill, snow, and frosty.
To "chip in" means to add to or add some in to.
Some examples of words where you drop the "y" and add "ied" are "cry" to "cried," "try" to "tried," and "copy" to "copied."
boxesfixespoxesmixesfaxesduxeswaxessixeshexes
addplus add on to
augment- to increase, to add to
Some words that end in the vowel y and add es to form the plural are alley, journey, and key.
plus sum add quantity
The words ate, it, date, eat, air, and tie. But feel free to add more words if you find some.
more, plus, deposit, add, gain, raise, increase, sum, total
Here are some: [feel free to add]hopelessnessassesssessionsscissorsendlessness
Some words you get are:sloopslopesloshsloth