A common pattern among irregular English verbs is characterized by the change in pronunciation /iːd/ → /ɛd/ in the past tense and past participle. There are two types of such verbs. Those ending with -eed are the following:
breed – bred – bred; also “crossbreed”, “inbreed”, and “interbreed”
feed – fed – fed; also “overfeed”
speed – sped or speeded – sped or speeded
Both “speeded” and “sped” can be used as the past tense and past participle of “speed”, but “sped” is somewhat more common.
The other (not very large) category of verbs following the same pattern are those in which -ead changes to -ed:
plead – pleaded or pled – pleaded or pled (see below)
Although both “pleaded” and “pled” have been around for a while, most speakers use the former form. “Pled” is gaining popularity in American English (but not so much in British English), but some speakers still consider “pled” to be incorrect. It is therefore advisable for an English learner to avoid it and use “pleaded” instead.
Finally, there are two verbs following a similar pattern:
flee – fled – fled