You can do this yourself you know (!)
I am not sure if sherds get lectures to themselves
( see Mosaics contribution)
This lot:
http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511558207&cid=CBO9780511558207A023
got on their hands and knees in Nubia actually, and said - 5 cm we got type A, 10cms type B so type B has to precede type A but we are not sure of the time......
relative dating - Flinders Petrie started it all
so go off to your local museum and look at the cabinet of 15th cent pott and think - oh it looks like that - and then stare at the 16th cent pott cabinet and think Oh, it look like THAT and then stare at the ....
oh and photograph them and keep a catalogue
since you are finding them on a surface then stratigraphy ( = the context ) is no real help and so you only ever get rough dates
[ oh god it shows I have worked on an archeological site innit ? Nubia actually 1980 ]
[ My brother got a bronze ax head on the surface and I squealed - is this a joke, did you buy this ? and we thought probably when the garding was redone in the 1850s they had got a job lot of earth from somewhere .... )